CH18, CH20, CH23, CH25, CH640, CH730, CH740
Liquefi ed Petroleum Gas (LPG) or LPG/Natural Gas (NG) Fueled
Service Manual
2 Safety
3 Maintenance
5 Specifi cations
13 Tools and Aids
16 Troubleshooting
20 Air Cleaner/Intake
21 Fuel System
30 Governor System
32 Lubrication System
34 Electrical System
50 Starter System
57 Disassembly/Inspection and Service
73 Reassembly
IMPORTANT: Read all safety precautions and instructions carefully before operating equipment. Refer to operating
instruction of equipment that this engine powers.
Ensure engine is stopped and level before performing any maintenance or service.
124 690 30 Rev. G KohlerEngines.com
Safety
2 24 690 30 Rev. GKohlerEngines.com
SAFETY PRECAUTIONS
WARNING: A hazard that could result in death, serious injury, or substantial property damage.
CAUTION: A hazard that could result in minor personal injury or property damage.
NOTE: is used to notify people of important installation, operation, or maintenance information.
WARNING
Explosive Fuel can
cause fi res and severe
burns.
If a gaseous odor is
detected, ventilate
area and contact an
authorized service
technician.
LPG is extremely fl ammable and
is heavier than air and tends to
settle in low areas where a spark
or fl ame could ignite gas. Do not
start or operate this engine in
a poorly ventilated area where
leaking gas could accumulate and
endanger safety of persons in
area.
NG is extremely fl ammable, is
lighter than air, and rises. Do not
start or operate this engine in
a poorly ventilated area where
leaking gas could accumulate and
endanger safety of persons in
area.
To ensure personal safety,
installation and repair of LPG/
NG fuel supply systems must
be performed only by qualifi ed
LPG/NG system technicians.
Improperly installed and
maintained LPG/NG equipment
could cause fuel supply system or
other components to malfunction,
causing gas leaks.
Observe federal, state and local
laws governing LPG/NG fuel,
storage, and systems.
WARNING
Rotating Parts can cause
severe injury.
Stay away while engine
is in operation.
Keep hands, feet, hair, and
clothing away from all moving
parts to prevent injury. Never
operate engine with covers,
shrouds, or guards removed.
WARNING
Carbon Monoxide can
cause severe nausea,
fainting or death.
Avoid inhaling exhaust
fumes. Never run engine
indoors or in enclosed
spaces.
Engine exhaust gases contain
poisonous carbon monoxide.
Carbon monoxide is odorless,
colorless, and can cause death if
inhaled.
WARNING
Accidental Starts can
cause severe injury or
death.
Disconnect and ground
spark plug lead(s) before
servicing.
Before working on engine or
equipment, disable engine as
follows: 1) Disconnect spark plug
lead(s). 2) Disconnect negative (–)
battery cable from battery.
Before disconnecting negative
(–) ground cable, make sure all
switches are OFF. If ON, a spark
will occur at ground cable terminal
which could cause an explosion
if hydrogen gas or LPG/NG fuel
vapors are present.
WARNING
Hot Parts can cause
severe burns.
Do not touch engine
while operating or just
after stopping.
Never operate engine with heat
shields or guards removed.
WARNING
Cleaning Solvents can
cause severe injury or
death.
Use only in well
ventilated areas away
from ignition sources.
Carburetor cleaners and solvents
are extremely fl ammable. Follow
cleaner manufacturer’s warnings
and instructions on its proper and
safe use. Never use gasoline as a
cleaning agent.
CAUTION
Electrical Shock can
cause injury.
Do not touch wires while
engine is running.
CAUTION
Damaging Crankshaft
and Flywheel can cause
personal injury.
Using improper procedures can
lead to broken fragments. Broken
fragments could be thrown from
engine. Always observe and use
precautions and procedures when
installing fl ywheel.
CAUTION
Failure to utilize or
reassemble debris
screen as designed could
result in debris screen
failure and serious
personal injury.
Maintenance
324 690 30 Rev. G KohlerEngines.com
MAINTENANCE INSTRUCTIONS
WARNING
Before working on engine or equipment, disable engine as
follows: 1) Disconnect spark plug lead(s). 2) Disconnect
negative (–) battery cable from battery.
Before disconnecting negative (–) ground cable, make
sure all switches are OFF. If ON, a spark will occur at
ground cable terminal which could cause an explosion if
hydrogen gas or LPG/NG fuel vapors are present.
Accidental Starts can cause severe injury or
death.
Disconnect and ground spark plug lead(s)
before servicing.
Normal maintenance, replacement or repair of emission control devices and systems may be performed by any repair
establishment or individual; however, warranty repairs must be performed by a Kohler authorized dealer.
MAINTENANCE SCHEDULE
Every 25 Hours
1
● Service precleaner element. Air Cleaner/Intake
Every 100 Hours
1
● Check oil cooler fi ns, clean as necessary (if equipped). Air Cleaner/Intake
● Change oil. Lubrication System
● Replace air cleaner element. Air Cleaner/Intake
● Remove cooling shrouds and clean cooling areas. Air Cleaner/Intake
Every 200 Hours
1
● Change oil fi lter. Lubrication System
Every 300 Hours
3
● Change oil and fi lter (KOHLER PRO 10W-50 oil and KOHLER PRO fi lter only). Lubrication System
Every 500 Hours or Annually
1
(whichever comes fi rst)
● Check all lines (high pressure/vacuum) including fi ttings for leaks. Fuel System
● Drain regulator of accumulated fuel deposits. Fuel System
● Replace spark plugs and set gap. Electrical System
Every 500 Hours or Annually
1,2
(whichever comes fi rst)
● Have lock-off /fi lter serviced. Fuel System
Every 1500 Hours
1,2
● Have regulator disassembled, cleaned, and reset. Fuel System
● Have vaporizer disassembled, cleaned, and serviced. Fuel System
1
Perform these procedures more frequently under severe, dusty, dirty conditions.
2
Must be performed by a Kohler authorized dealer or qualifi ed LPG personnel only.
3
Option only if using KOHLER
®
PRO oil and PRO fi lter.
REPAIRS/SERVICE PARTS
Kohler genuine service parts can be purchased from Kohler authorized dealers. To fi nd a local Kohler authorized
dealer visit KohlerEngines.com or call 1-800-544-2444 (U.S. and Canada).
Maintenance
4 24 690 30 Rev. GKohlerEngines.com
OIL RECOMMENDATIONS
All-season KOHLER
®
PRO 10W-50 Synthetic Oil is the
ideal oil for KOHLER engines. It is specifi cally formulated
to extend the oil and oil fi lter change interval to 300
Hours when paired with a KOHLER PRO Extended Life
Oil Filter.
300-Hour oil and oil fi lter change intervals are exclusive
to and only authorized on KOHLER engines that utilize
both the KOHLER PRO 10W-50 Synthetic Oil and
KOHLER PRO Extended Life Oil Filter. Alternative
engine oils and oil fi lters may be used with KOHLER
engines but require 100-Hour oil and 200-Hour oil fi lter
change intervals for proper maintenance. Oil must be
API (American Petroleum Institute) service class SJ or
higher. Select viscosity based on air temperature at time
of operation as shown below.
°F
-20
020324060
50 80 100
°C
-30 -20
-10 0
10 20 30
40
5W-30
10W-30
SAE 30
Kohler PRO 10W-50
FUEL RECOMMENDATIONS
WARNING
Explosive Fuel can cause fi res and severe
burns.
If a gaseous odor is detected, ventilate area
and contact an authorized service technician.
LPG is extremely fl ammable and is heavier than air
and tends to settle in low areas where a spark or fl ame
could ignite gas. Do not start or operate this engine
in a poorly ventilated area where leaking gas could
accumulate and endanger safety of persons in area.
NG is extremely fl ammable, is lighter than air, and
rises. Do not start or operate this engine in a poorly
ventilated area where leaking gas could accumulate
and endanger safety of persons in area.
To ensure personal safety, installation and repair of
LPG/NG fuel supply systems must be performed only
by qualifi ed LPG/NG system technicians. Improperly
installed and maintained LPG/NG equipment could
cause fuel supply system or other components to
malfunction, causing gas leaks.
Observe federal, state and local laws governing LPG/
NG fuel, storage, and systems.
This engine is certifi ed to operate on LPG or LPG/NG.
LPG Engines
LPG from an appropriate LPG fuel tank (supplied
separately) is required to operate this engine.
NG Engines
NG from an approved system or source of supply can be
used to operate this engine.
STORAGE
If engine will be out of service for 2 months or more
follow procedure below.
1. Change oil while engine is still warm from operation
(NOT required if using KOHLER PRO 10W-50
full-synthetic oil). Remove spark plug(s) and pour
about 1 oz. of engine oil into cylinder(s). Replace
spark plug(s) and crank engine slowly to distribute
oil.
2. Disconnect negative (–) battery cable.
3. Separate LPG tank from unit and store separately in
an area designated for safe LPG tank storage.
4. Store engine in a clean, dry place.
Specifi cations
524 690 30 Rev. G KohlerEngines.com
Engine Dimensions
Dimensions in millimeters.
Inch equivalents shown in [ ].
Specifi cations
6 24 690 30 Rev. GKohlerEngines.com
ENGINE IDENTIFICATION NUMBERS
Kohler engine identifi cation numbers (model, specifi cation and serial) should be referenced for effi cient repair,
ordering correct parts, and engine replacement.
Model . . . . . . . . . . . . . . . . . . . . . CH640
Command Engine
Horizontal Shaft
Numerical Designation
Specifi cation . . . . . . . . . . . . . . . CH640-0001
Serial . . . . . . . . . . . . . . . . . . . . . 4923500328
Year Manufactured Code Factory Code
Code Year
49 2019
50 2020
51 2021
GENERAL SPECIFICATIONS
4,7
CH18/CH20/
CH640 CH23
CH25/
CH730/CH740
Bore 77 mm
(3.03 in.)
80 mm
(3.15 in.)
83 mm (3.27 in.)
Stroke 67 mm (2.64 in.)
Displacement 624 cc
(38 cu. in.)
674 cc
(41 cu. in.)
725 cc
(44 cu. in.)
Oil Capacity (refi ll) 1.6-1.8 L (1.7-1.9 U.S. qt.)
Maximum Angle of Operation (@ full oil level)
5
25°
TORQUE SPECIFICATIONS
4,6
CH18/CH20/
CH640 CH23
CH25/
CH730/CH740
Blower Housing and Sheet Metal
M5 Fasteners 6.2 N·m (55 in. lb.) into new holes
4.0 N·m (35 in. lb.) into used holes
M6 Fasteners 10.7 N·m (95 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
Carburetor and Intake Manifold
Intake Manifold Mounting Fastener (torque in 2
increments)
fi rst to 7.4 N·m (66 in. lb.)
fi nally to 9.9 N·m (88 in. lb.)
M6 Mounting Screw or Nut 6.2-7.3 N·m (55-65 in. lb.)
Closure Plate
Fastener 24.4 N·m (216 in. lb.)
Connecting Rod
Cap Fastener (torque in increments)
8 mm straight shank
8 mm step-down
6 mm straight shank
22.7 N·m (200 in. lb.)
14.7 N·m (130 in. lb.)
11.3 N·m (100 in. lb.)
4
Values are in Metric units. Values in parentheses are English equivalents.
5
Exceeding maximum angle of operation may cause engine damage from insuffi cient lubrication.
6
Lubricate threads with engine oil prior to assembly.
7
Any and all horsepower (hp) references by Kohler are Certifi ed Power Ratings and per SAE J1940 & J1995 hp
standards. Details on Certifi ed Power Ratings can be found at KohlerEngines.com.
Specifi cations
724 690 30 Rev. G KohlerEngines.com
TORQUE SPECIFICATIONS
4,6
CH18/CH20/
CH640 CH23
CH25/
CH730/CH740
Crankcase
Breather Cover Fastener 11.3 N·m (100 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
Oil Drain Plug 13.6 N·m (10 ft. lb.)
Cylinder Head
Fastener (torque in 2 increments)
Nut fi rst to 16.9 N·m (150 in. lb.)
fi nally to 35.5 N·m (315 in. lb.)
Bolt (torque in 2 increments) fi rst to 22.6 N·m (200 in. lb.)
fi nally to 41.8 N·m (370 in. lb.)
Rocker Arm Screw
Black Screw (M6x1.0x34)
Silver Screw (M6x1.0x45)
18.1 N·m (160 in. lb.)
13.6 N·m (120 in. lb.)
Flywheel
Fan Fastener 9.9 N·m (88 in. lb.)
Flywheel Retaining Screw 66.4 N·m (49 ft. lb.)
Governor
Lever Nut 6.8 N·m (60 in. lb.)
Ignition
Spark Plug 27 N·m (20 ft. lb.)
Module Fastener 4.0-6.2 N·m (35-55 in. lb.)
Rectifi er-Regulator Fastener 1.4 N·m (12.6 in. lb.)
Muffl er
Retaining Nut 24.4 N·m (216 in. lb.)
Oil Cooler
Adapter Nipple 27 N·m (20 ft. lb.)
Oil Sentry
™
Pressure Switch 4.5 N·m (40 in. lb.)
Regulator
Bracket Screws 22.6 N·m (200 in. lb.)
Screws 24.4 N·m (216 in. lb.)
Solenoid (Starter)
Mounting Hardware
Nippondenso Starter
Delco-Remy Starter
6.0-9.0 N·m (53-79 in. lb.)
4.0-6.0 N·m (35-53 in. lb.)
Nut, Positive (+) Brush Lead
Nippondenso Starter
Delco-Remy Starter
8.0-12.0 N·m (71-106 in. lb.)
8.0-11.0 N·m (71-97 in. lb.)
Speed Control Bracket
Fastener 10.7 N·m (95 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
4
Values are in Metric units. Values in parentheses are English equivalents.
6
Lubricate threads with engine oil prior to assembly.
Specifi cations
8 24 690 30 Rev. GKohlerEngines.com
TORQUE SPECIFICATIONS
4,6
CH18/CH20/
CH640 CH23
CH25/
CH730/CH740
Starter Assembly
Thru Bolt
Inertia Drive
Nippondenso Solenoid Shift
Delco-Remy Solenoid Shift
4.5-5.7 N·m (40-50 in. lb.)
4.5-7.5 N·m (40-84 in. lb.)
5.6-9.0 N·m (49-79 in. lb.)
Mounting Screw 15.3 N·m (135 in. lb.)
Brush Holder Mounting Screw 2.5-3.3 N·m (22-29 in. lb.)
Stator
Mounting Screw 6.2 N·m (55 in. lb.)
Valve Cover
Gasket Style Cover Fastener 3.4 N·m (30 in. lb.)
Black O-ring Style Cover Fastener
w/Shoulder Screws
w/Flange Screws and Spacers
5.6 N·m (50 in. lb.)
9.9 N·m (88 in. lb.)
Yellow or Brown O-ring Style Cover Fastener
w/Integral Metal Spacers 9.0 N·m (80 in. lb.)
Vaporizer
3/8 in. Screw 29.4 N·m (260 in. lb.)
1/4 in. Screw 7.9 N·m (70 in. lb.)
CLEARANCE SPECIFICATIONS
4
CH18/CH20/
CH640 CH23
CH25/
CH730/CH740
Camshaft
End Play (w/shim) 0.076/0.127 mm (0.0030/0.0050 in.)
Running Clearance 0.025/0.063 mm (0.0010/0.0025 in.)
Bore I.D.
New
Max. Wear Limit
20.000/20.025 mm (0.7874/0.7884 in.)
20.038 mm (0.7889 in.)
Bearing Surface O.D.
New
Max. Wear Limit
19.962/19.975 mm (0.7859/0.7864 in.)
19.959 mm (0.7858 in.)
Connecting Rod
Connecting Rod-to-Crankpin Running Clearance
New
Max. Wear Limit
0.030/0.055 mm (0.0012/0.0022 in.)
0.070 mm (0.0028 in.)
Connecting Rod-to-Crankpin Side Clearance 0.26/0.63 mm (0.0102/0.0248 in.)
Connecting Rod-to-Piston Pin Running Clearance 0.015/0.028 mm (0.0006/0.0011 in.)
Piston Pin End I.D.
New
Max. Wear Limit
17.015/17.023 mm (0.6699/0.6702 in.)
17.036 mm (0.6707 in.)
4
Values are in Metric units. Values in parentheses are English equivalents.
6
Lubricate threads with engine oil prior to assembly.
Specifi cations
924 690 30 Rev. G KohlerEngines.com
CLEARANCE SPECIFICATIONS
4
CH18/CH20/
CH640 CH23
CH25/
CH730/CH740
Crankcase
Governor Cross Shaft Bore I.D.
6 mm Shaft
New
Max. Wear Limit
8 mm Shaft
New
Max. Wear Limit
6.025/6.050 mm (0.2372/0.2382 in.)
6.063 mm (0.2387 in.)
8.025/8.075 mm (0.3159/0.3179 in.)
8.088 mm (0.3184 in.)
Crankshaft
End Play (free) 0.070/0.590 mm (0.0028/0.0230 in.)
End Play (w/thrust bearing components) 0.070/1.190 mm (0.0028/0.0468 in.)
Except CH25 Engines Below Serial No. 2403500008 0.050/0.750 mm (0.0020/0.0295 in.)
Bore (in crankcase)
New
Max. Wear Limit
40.965/41.003 mm (1.6128/1.6143 in.)
41.016 mm (1.6148 in.)
Crankshaft to Sleeve Bearing (crankcase)
Running Clearance-New 0.03/0.09 mm (0.0012/0.0035 in.)
Bore (in closure plate)
New 40.987/40.974 mm (1.6136/1.6131 in.)
Crankshaft Bore (in closure plate)-to-Crankshaft
Running Clearance-New 0.039/0.074 mm (0.0015/0.0029 in.)
Flywheel End Main Bearing Journal
O.D. - New
O.D. - Max. Wear Limit
Max. Taper
Max. Out-of-Round
40.913/40.935 mm (1.6107/1.6116 in.)
40.84 mm (1.608 in.)
0.022 mm (0.0009 in.)
0.025 mm (0.0010 in.)
Closure Plate End Main Bearing Journal
O.D. - New
O.D. - Max. Wear Limit
Max. Taper
Max. Out-of-Round
40.913/40.935 mm (1.6107/1.6116 in.)
40.84 mm (1.608 in.)
0.022 mm (0.0009 in.)
0.025 mm (0.0010 in.)
Connecting Rod Journal
O.D. - New
O.D. - Max. Wear Limit
Max. Taper
Max. Out-of-Round
35.955/35.973 mm (1.4156/1.4163 in.)
35.94 mm (1.415 in.)
0.018 mm (0.0007 in.)
0.025 mm (0.0010 in.)
T.I.R.
PTO End, Crank in Engine
Entire Crank, in V-Blocks
0.279 mm (0.0110 in.)
0.10 mm (0.0039 in.)
Cylinder Bore
Bore I.D.
New 77.000/77.025 mm
(3.0315/3.0325 in.)
80.000/80.025 mm
(3.1496/3.1506 in.)
82.988/83.013 mm
(3.2672/3.2682 in.)
Max. Wear Limit 77.063 mm
(3.0340 in.)
80.065 mm
(3.1522 in.)
83.051 mm
(3.2697 in.)
Max. Out-of-Round 0.12 mm (0.0047 in.)
Max. Taper 0.05 mm (0.0020 in.)
4
Values are in Metric units. Values in parentheses are English equivalents.
Specifi cations
10 24 690 30 Rev. GKohlerEngines.com
CLEARANCE SPECIFICATIONS
4
CH18/CH20/
CH640 CH23
CH25/
CH730/CH740
Cylinder Head
Max. Out-of-Flatness 0.076 mm (0.003 in.) 0.1 mm (0.004 in.)
Governor
Governor Cross Shaft-to-Crankcase
Running Clearance
6 mm Shaft
8 mm Shaft
0.013/0.075 mm (0.0005/0.0030 in.)
0.025/0.126 mm (0.0009/0.0049 in.)
Cross Shaft O.D.
6 mm Shaft
New
Max. Wear Limit
8 mm Shaft
New
Max. Wear Limit
5.975/6.012 mm (0.2352/0.2367 in.)
5.962 mm (0.2347 in.)
7.949/8.000 mm (0.3129/0.3149 in.)
7.936 mm (0.3124 in.)
Governor Gear Shaft-to-Governor Gear
Running Clearance
0.015/0.140 mm (0.0006/0.0055 in.)
Gear Shaft O.D.
New
Max. Wear Limit
5.990/6.000 mm (0.2358/0.2362 in.)
5.977 mm (0.2353 in.)
Ignition
Spark Plug Gap 0.76 mm (0.030 in.) for All Except NG with CD Fixed
0.51 mm (0.020 in.) for NG with CD Fixed
Module Air Gap 0.28/0.33 mm (0.011/0.013 in.)
Piston, Piston Rings, and Piston Pin
Piston-to-Piston Pin Running Clearance 0.006/0.017 mm (0.0002/0.0007 in.)
Pin Bore I.D.
New
Max. Wear Limit
17.006/17.012 mm (0.6695/0.6698 in.)
17.025 mm (0.6703 in.)
Pin O.D.
New
Max. Wear Limit
16.995/17.000 mm (0.6691/0.6693 in.)
16.994 mm (0.6691 in.)
Top Compression Ring-to-Groove Side Clearance 0.040/0.080 mm
(0.0016/0.0031 in.)
0.030/0.076 mm
(0.0012/0.0030 in.)
0.025/0.048 mm
(0.0010/0.0019 in.)
Middle Compression Ring-to-Groove Side Clearance 0.040/0.080 mm
(0.0016/0.0031 in.)
0.030/0.076 mm
(0.0012/0.0030 in.)
0.015/0.037 mm
(0.0006/0.0015 in.)
Oil Control Ring-to-Groove Side Clearance 0.060/0.202 mm
(0.0024/0.0080 in.)
0.046/0.196 mm
(0.0018/0.0077 in.)
0.026/0.176 mm
(0.0010/0.0070 in.)
Top and Middle Compression Ring End Gap
New Bore 0.25/0.45 mm
(0.0098/0.0177 in.)
0.18/0.46 mm
(0.0071/0.0181 in.)
0.25/0.56 mm
(0.0100/0.0224 in.)
Used Bore (Max) 0.77 mm
(0.030 in.)
0.80 mm
(0.0315 in.)
0.94 mm
(0.037 in.)
Thrust Face O.D.
8
New 76.943/76.961 mm
(3.0292/3.0299 in.)
79.943/79.961 mm
(3.1473/3.1480 in.)
82.949/82.967 mm
(3.2656/3.2664 in.)
Max. Wear Limit 76.816 mm
(3.0242 in.)
79.816 mm
(3.1423 in.)
82.822 mm
(3.2606 in.)
Piston Thrust Face-to-Cylinder Bore
8
Running
Clearance
New
0.039/0.082 mm
(0.0015/0.0032 in.)
4
Values are in Metric units. Values in parentheses are English equivalents.
8
Measure 6 mm (0.24 in.) above bottom of piston skirt at right angles to piston pin.
Specifi cations
1124 690 30 Rev. G KohlerEngines.com
CLEARANCE SPECIFICATIONS
4
CH18/CH20/
CH640 CH23
CH25/
CH730/CH740
Valves and Valve Lifters
Hydraulic Valve Lifter to Crankcase Running Clearance 0.0241/0.0501 mm (0.0009/0.0020 in.)
Intake Valve Stem-to-Valve Guide Running Clearance 0.038/0.076 mm (0.0015/0.0030 in.)
Exhaust Valve Stem-to-Valve Guide Running Clearance 0.050/0.088 mm (0.0020/0.0035 in.)
Intake Valve Guide I.D.
New
Max. Wear Limit
7.038/7.058 mm (0.2771/0.2779 in.)
7.134 mm (0.2809 in.)
Exhaust Valve Guide I.D.
New
Max. Wear Limit
7.038/7.058 mm (0.2771/0.2779 in.)
7.159 mm (0.2819 in.)
Valve Guide Reamer Size
Standard
0.25 mm O.S.
7.048 mm (0.2775 in.)
7.298 mm (0.2873 in.)
Intake Valve Minimum Lift 8.07 mm (0.3177 in.)
Exhaust Valve Minimum Lift 8.07 mm (0.3177 in.)
Nominal Valve Seat Angle 45°
4
Values are in Metric units. Values in parentheses are English equivalents.
Specifi cations
12 24 690 30 Rev. GKohlerEngines.com
GENERAL TORQUE VALUES
Metric Fastener Torque Recommendations for Standard Applications
Property Class
Noncritical
Fasteners
Into Aluminum
Size
4.8
5.8
8.8
10.9 12.9
Tightening Torque: N·m (in. lb.) ± 10%
M4 1.2 (11) 1.7 (15) 2.9 (26) 4.1 (36) 5.0 (44) 2.0 (18)
M5 2.5 (22) 3.2 (28) 5.8 (51) 8.1 (72) 9.7 (86) 4.0 (35)
M6 4.3 (38) 5.7 (50) 9.9 (88) 14.0 (124) 16.5 (146) 6.8 (60)
M8 10.5 (93) 13.6 (120) 24.4 (216) 33.9 (300) 40.7 (360) 17.0 (150)
Tightening Torque: N·m (ft. lb.) ± 10%
M10 21.7 (16) 27.1 (20) 47.5 (35) 66.4 (49) 81.4 (60) 33.9 (25)
M12 36.6 (27) 47.5 (35) 82.7 (61) 116.6 (86) 139.7 (103) 61.0 (45)
M14 58.3 (43) 76.4 (56) 131.5 (97) 184.4 (136) 219.7 (162) 94.9 (70)
Torque Conversions
N·m = in. lb. x 0.113 in. lb. = N·m x 8.85
N·m = ft. lb. x 1.356 ft. lb. = N·m x 0.737
English Fastener Torque Recommendations for Standard Applications
Bolts, Screws, Nuts and Fasteners Assembled Into Cast Iron or Steel
Grade 2 or 5 Fasteners
Into Aluminum
Size Grade 2 Grade 5 Grade 8
Tightening Torque: N·m (in. lb.) ± 20%
8-32 2.3 (20) 2.8 (25) — 2.3 (20)
10-24 3.6 (32) 4.5 (40) — 3.6 (32)
10-32 3.6 (32) 4.5 (40) — —
1/4-20 7.9 (70) 13.0 (115) 18.7 (165) 7.9 (70)
1/4-28 9.6 (85) 15.8 (140) 22.6 (200) —
5/16-18 17.0 (150) 28.3 (250) 39.6 (350) 17.0 (150)
5/16-24 18.7 (165) 30.5 (270) — —
3/8-16 29.4 (260) — — —
3/8-24 33.9 (300) — — —
Tightening Torque: N·m (ft. lb.) ± 20%
5/16-24 — — 40.7 (30) —
3/8-16 — 47.5 (35) 67.8 (50) —
3/8-24 — 54.2 (40) 81.4 (60) —
7/16-14 47.5 (35) 74.6 (55) 108.5 (80) —
7/16-20 61.0 (45) 101.7 (75) 142.5 (105) —
1/2-13 67.8 (50) 108.5 (80) 155.9 (115) —
1/2-20 94.9 (70) 142.4 (105) 223.7 (165) —
9/16-12 101.7 (75) 169.5 (125) 237.3 (175) —
9/16-18 135.6 (100) 223.7 (165) 311.9 (230) —
5/8-11 149.5 (110) 244.1 (180) 352.6 (260) —
5/8-18 189.8 (140) 311.9 (230) 447.5 (330) —
3/4-10 199.3 (147) 332.2 (245) 474.6 (350) —
3/4-16 271.2 (200) 440.7 (325) 637.3 (470) —
Tools and Aids
1324 690 30 Rev. G KohlerEngines.com
Certain quality tools are designed to help you perform specifi c disassembly, repair, and reassembly procedures. By
using these tools, you can properly service engines easier, faster, and safer! In addition, you’ll increase your service
capabilities and customer satisfaction by decreasing engine downtime.
Here is a list of tools and their source.
NOTE: Not all tools listed are required to service this engine.
SEPARATE TOOL SUPPLIERS
Kohler Tools
Contact your local Kohler source of
supply.
SE Tools
415 Howard St.
Lapeer, MI 48446
Phone 810-664-2981
Toll Free 800-664-2981
Fax 810-664-8181
Design Technology Inc.
768 Burr Oak Drive
Westmont, IL 60559
Phone 630-920-1300
Fax 630-920-0011
TOOLS
Description Source/Part No.
Alcohol Content Tester
For testing alcohol content (%) in reformulated/oxygenated fuels.
Kohler 25 455 11-S
Camshaft Endplay Plate
For checking camshaft endplay.
SE Tools KLR-82405
Camshaft Seal Protector (Aegis)
For protecting seal during camshaft installation.
SE Tools KLR-82417
Cylinder Leakdown Tester
For checking combustion retention and if cylinder, piston, rings, or valves are worn.
Individual component available:
Adapter 12 mm x 14 mm (Required for leakdown test on XT-6 engines)
Kohler 25 761 05-S
Design Technology Inc.
DTI-731-03
Dealer Tool Kit (Domestic)
Complete kit of Kohler required tools.
Components of 25 761 39-S
Ignition System Tester
Cylinder Leakdown Tester
Oil Pressure Test Kit
Rectifi er-Regulator Tester (120 V AC/60Hz)
Kohler 25 761 39-S
Kohler 25 455 01-S
Kohler 25 761 05-S
Kohler 25 761 06-S
Kohler 25 761 20-S
Dealer Tool Kit (International)
Complete kit of Kohler required tools.
Components of 25 761 42-S
Ignition System Tester
Cylinder Leakdown Tester
Oil Pressure Test Kit
Rectifi er-Regulator Tester (240 V AC/50Hz)
Kohler 25 761 42-S
Kohler 25 455 01-S
Kohler 25 761 05-S
Kohler 25 761 06-S
Kohler 25 761 41-S
Digital Vacuum/Pressure Tester
For checking crankcase vacuum.
Individual component available:
Rubber Adapter Plug
Design Technology Inc.
DTI-721-01
Design Technology Inc.
DTI-721-10
Electronic Fuel Injection (EFI) Diagnostic Software
For Laptop or Desktop PC.
Kohler 25 761 23-S
EFI Service Kit
For troubleshooting and setting up an EFI engine.
Components of 24 761 01-S
Fuel Pressure Tester
Noid Light
90° Adapter
Code Plug, Red Wire
Code Plug, Blue Wire
Shrader Valve Adapter Hose
Wire Probe Set (2 pieces regular wire with clip; 1 piece fused wire)
Hose Removal Tool, Dual Size/End (also sold as individual Kohler tool)
K-Line Adapter Jumper Lead Wiring Harness
Kohler 24 761 01-S
Design Technology Inc.
DTI-019
DTI-021
DTI-023
DTI-027
DTI-029
DTI-037
DTI-031
DTI-033
Kohler 25 176 23-S
Kohler Wireless Diagnostic System Module (Bluetooth®)
For wireless Android EFI diagnostics.
Individual component available:
Wireless Diagnostic System Interface Cable
Kohler 25 761 45-S
Kohler 25 761 44-S
Tools and Aids
14 24 690 30 Rev. GKohlerEngines.com
TOOLS
Description Source/Part No.
Flywheel Puller
For properly removing fl ywheel from engine.
SE Tools KLR-82408
Flywheel Anchor Bolts, Washers, Nuts Tool
Used with Flywheel Puller for properly removing fl ywheel from 5400 Series engine.
Kohler 25 086 753-S
Hose Removal Tool, Dual Size/End (also available in EFI Service Kit)
Used to properly remove fuel hose from engine components.
Kohler 25 455 20-S
Hydraulic Valve Lifter Tool
For removing and installing hydraulic lifters.
Kohler 25 761 38-S
Ignition System Tester
For testing output on all systems, including CD.
Kohler 25 455 01-S
Inductive Tachometer (Digital)
For checking operating speed (RPM) of an engine.
Design Technology Inc.
DTI-110
Off set Wrench (K and M Series)
For removing and reinstalling cylinder barrel retaining nuts.
Kohler 52 455 04-S
Oil Pressure Test Kit
For testing/verifying oil pressure on pressure lubricated engines.
Kohler 25 761 06-S
Rectifi er-Regulator Tester (120 volt current)
Rectifi er-Regulator Tester (240 volt current)
For testing rectifi er-regulators.
Components of 25 761 20-S and 25 761 41-S
CS-PRO Regulator Test Harness
Special Regulator Test Harness with Diode
Kohler 25 761 20-S
Kohler 25 761 41-S
Design Technology Inc.
DTI-031R
DTI-033R
Spark Advance Module (SAM) Tester
For testing SAM (ASAM and DSAM) on engines with SMART-SPARK
™
.
Kohler 25 761 40-S
Starter Servicing Kit (All Starters)
For removing and reinstalling drive retaining rings and brushes.
Individual component available:
Starter Brush Holding Tool (Solenoid Shift)
SE Tools KLR-82411
SE Tools KLR-82416
Stepper Motor Controller Tool
For testing operation of stepper motor/Digital Linear Actuator (DLA).
Kohler 25 455 21-S
Jumper Lead Tool
For use with Stepper Motor Controller Tool to test rotary stepper motor.
Kohler 25 518 43-S
Triad/OHC Timing Tool Set
For holding cam gears and crankshaft in timed position while installing timing belt.
Kohler 28 761 01-S
Valve Guide Reamer (K and M Series)
For properly sizing valve guides after installation.
Design Technology Inc.
DTI-K828
Valve Guide Reamer O.S. (Command Series)
For reaming worn valve guides to accept replacement oversize valves. Can be used
in low-speed drill press or with handle below for hand reaming.
Kohler 25 455 12-S
Reamer Handle
For hand reaming using Kohler 25 455 12-S reamer.
Design Technology Inc.
DTI-K830
Tools and Aids
1524 690 30 Rev. G KohlerEngines.com
FLYWHEEL HOLDING TOOL ROCKER ARM/CRANKSHAFT TOOL
A fl ywheel holding tool can be made out of an old junk
fl ywheel ring gear and used in place of a strap wrench.
1. Using an abrasive cut-off wheel, cut out a six tooth
segment of ring gear as shown.
2. Grind off any burrs or sharp edges.
3. Invert segment and place it between ignition bosses
on crankcase so tool teeth engage fl ywheel ring
gear teeth. Bosses will lock tool and fl ywheel in
position for loosening, tightening, or removing with a
puller.
A spanner wrench to lift rocker arms or turn crankshaft
may be made out of an old junk connecting rod.
1. Find a used connecting rod from a 10 HP or larger
engine. Remove and discard rod cap.
2. Remove studs of a Posi-Lock rod or grind off
aligning steps of a Command rod, so joint surface is
fl at.
3. Find a 1 in. long capscrew with correct thread size to
match threads in connecting rod.
4. Use a fl at washer with correct I.D. to slip on
capscrew and approximately 1 in. O.D. Assemble
capscrew and washer to joint surface of rod.
AIDS
Description Source/Part No.
Camshaft Lubricant (Valspar ZZ613) Kohler 25 357 14-S
Dielectric Grease (GE/Novaguard G661) Kohler 25 357 11-S
Dielectric Grease Loctite
®
51360
Kohler Electric Starter Drive Lubricant (Inertia Drive) Kohler 52 357 01-S
Kohler Electric Starter Drive Lubricant (Solenoid Shift) Kohler 52 357 02-S
RTV Silicone Sealant
Loctite
®
5900
®
Heavy Body in 4 oz. aerosol dispenser.
Only oxime-based, oil resistant RTV sealants, such as those listed, are approved
for use. Permatex
®
the Right Stuff
®
1 Minute Gasket™ or Loctite
®
Nos. 5900
®
or
5910
®
are recommended for best sealing characteristics.
Kohler 25 597 07-S
Loctite
®
5910
®
Loctite
®
Ultra Black 598™
Loctite
®
Ultra Blue 587™
Loctite
®
Ultra Copper 5920™
Permatex
®
the Right Stuff
®
1
Minute Gasket™
Spline Drive Lubricant Kohler 25 357 12-S
Troubleshooting
16 24 690 30 Rev. GKohlerEngines.com
Engine Cranks But Will Not Start
● Battery connected backwards.
● Blown fuse.
● Carburetor solenoid malfunction.
● Choke not closing.
● Clogged fuel line or fuel fi lter.
● Diode in wiring harness failed in open circuit mode.
● DSAI or DSAM malfunction.
● Empty fuel tank.
● Faulty electronic control unit.
● Faulty ignition coil(s).
● Faulty spark plug(s).
● Fuel pump malfunction-vacuum hose clogged or
leaking.
● Fuel shut-off valve closed.
● Ignition module(s) faulty or improperly gapped.
● Insuffi cient voltage to electronic control unit.
● Interlock switch is engaged or faulty.
● Key switch or kill switch in OFF position.
● Low oil level.
● Quality of fuel (dirt, water, stale, mixture).
● SMART-SPARK
TM
malfunction.
● Spark plug lead(s) disconnected.
Engine Starts But Does Not Keep Running
● Faulty carburetor.
● Faulty cylinder head gasket.
● Faulty or misadjusted choke or throttle controls.
● Fuel pump malfunction-vacuum hose clogged or
leaking.
● Intake system leak.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Quality of fuel (dirt, water, stale, mixture).
● Restricted fuel tank cap vent.
Engine Starts Hard
● Clogged fuel line or fuel fi lter.
● Engine overheated.
● Faulty ACR mechanism.
● Faulty or misadjusted choke or throttle controls.
● Faulty spark plug(s).
● Flywheel key sheared.
● Fuel pump malfunction-vacuum hose clogged or
leaking.
● Interlock switch is engaged or faulty.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Low compression.
● Quality of fuel (dirt, water, stale, mixture).
● Weak spark.
TROUBLESHOOTING GUIDE
When troubles occur, be sure to check simple causes which, at fi rst, may seem too obvious to be considered. For
example, a starting problem could be caused by an empty fuel tank.
Some general common causes of engine troubles are listed below and vary by engine specifi cation. Use these to
locate causing factors.
Engine Will Not Crank
● Battery is discharged.
● Faulty electric starter or solenoid.
● Faulty key switch or ignition switch.
● Interlock switch is engaged or faulty.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Pawls not engaging in drive cup.
● Seized internal engine components.
Engine Runs But Misses
● Carburetor adjusted incorrectly.
● Engine overheated.
● Faulty spark plug(s).
● Ignition module(s) faulty or improperly gapped.
● Incorrect crankshaft position sensor air gap.
● Interlock switch is engaged or faulty.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Quality of fuel (dirt, water, stale, mixture).
● Spark plug lead(s) disconnected.
● Spark plug lead boot loose on plug.
● Spark plug lead loose.
Engine Will Not Idle
● Engine overheated.
● Faulty spark plug(s).
● Idle fuel adjusting needle(s) improperly set.
● Idle speed adjusting screw improperly set.
● Inadequate fuel supply.
● Low compression.
● Quality of fuel (dirt, water, stale, mixture).
● Restricted fuel tank cap vent.
Engine Overheats
● Cooling fan broken.
● Excessive engine load.
● Fan belt failed/off .
● Faulty carburetor.
● High crankcase oil level.
● Lean fuel mixture.
● Low cooling system fl uid level.
● Low crankcase oil level.
● Radiator, and/or cooling system components clogged,
restricted, or leaking.
● Water pump belt failed/broken.
● Water pump malfunction.
Engine Knocks
● Excessive engine load.
● Hydraulic lifter malfunction.
● Incorrect oil viscosity/type.
● Internal wear or damage.
● Low crankcase oil level.
● Quality of fuel (dirt, water, stale, mixture).
1724 690 30 Rev. G KohlerEngines.com
Troubleshooting
Engine Loses Power
● Dirty air cleaner element.
● Engine overheated.
● Excessive engine load.
● Restricted exhaust.
● Faulty spark plug(s).
● High crankcase oil level.
● Incorrect governor setting.
● Low battery.
● Low compression.
● Low crankcase oil level.
● Quality of fuel (dirt, water, stale, mixture).
Engine Uses Excessive Amount of Oil
● Loose or improperly torqued fasteners.
● Blown head gasket/overheated.
● Breather reed broken.
● Clogged, broken, or inoperative crankcase breather.
● Crankcase overfi lled.
● Incorrect oil viscosity/type.
● Worn cylinder bore.
● Worn or broken piston rings.
● Worn valve stems/valve guides.
Oil Leaks from Oil Seals, Gaskets
● Breather reed broken.
● Clogged, broken, or inoperative crankcase breather.
● Loose or improperly torqued fasteners.
● Piston blow by, or leaky valves.
● Restricted exhaust.
EXTERNAL ENGINE INSPECTION
NOTE: It is good practice to drain oil at a location away
from workbench. Be sure to allow ample time for
complete drainage.
Before cleaning or disassembling engine, make a
thorough inspection of its external appearance and
condition. This inspection can give clues to what
might be found inside engines (and cause) when it is
disassembled.
● Check for buildup of dirt and debris on crankcase,
cooling fi ns, grass screen, and other external surfaces.
Dirt or debris on these areas can cause overheating.
● Check for obvious fuel and oil leaks, and damaged
components. Excessive oil leakage can indicate a
clogged or inoperative breather, worn or damaged
seals or gaskets, or loose fasteners.
● Check air cleaner cover and base for damage or
indications of improper fi t and seal.
● Check air cleaner element. Look for holes, tears,
cracked or damaged sealing surfaces, or other
damage that could allow unfi ltered air into engine. A
dirty or clogged element could indicate insuffi cient or
improper maintenance.
● Check carburetor throat for dirt. Dirt in throat is further
indication that air cleaner was not functioning properly.
● Check if oil level is within operating range on dipstick.
If it is above, sniff for gasoline odor.
● Check condition of oil. Drain oil into a container; it
should fl ow freely. Check for metal chips and other
foreign particles.
Sludge is a natural by-product of combustion; a small
accumulation is normal. Excessive sludge formation
could indicate over rich fuel settings, weak ignition,
overextended oil change interval or wrong weight or
type of oil was used.
CLEANING ENGINE
WARNING
Cleaning Solvents can cause severe injury or
death.
Use only in well ventilated areas away from
ignition sources.
Carburetor cleaners and solvents are extremely
fl ammable. Follow cleaner manufacturer’s warnings
and instructions on its proper and safe use. Never use
gasoline as a cleaning agent.
After inspecting external condition of engine, clean
engine thoroughly before disassembly. Clean individual
components as engine is disassembled. Only clean
parts can be accurately inspected and gauged for wear
or damage. There are many commercially available
cleaners that will quickly remove grease, oil, and grime
from engine parts. When such a cleaner is used, follow
manufacturer’s instructions and safety precautions
carefully.
Make sure all traces of cleaner are removed before
engine is reassembled and placed into operation. Even
small amounts of these cleaners can quickly break down
lubricating properties of engine oil.
Troubleshooting
18 24 690 30 Rev. GKohlerEngines.com
Condition Conclusion
Crankcase breather clogged or inoperative. NOTE: If breather is integral part of valve cover and
cannot be serviced separately, replace valve
cover and recheck pressure.
Disassemble breather, clean parts thoroughly, check
sealing surfaces for fl atness, reassemble, and recheck
pressure.
Seals and/or gaskets leaking. Loose or improperly torque
fasteners.
Replace all worn or damaged seals and gaskets. Make
sure all fasteners are tightened securely. Use appropriate
torque valves and sequences when necessary.
Piston blow by or leaky valves (confi rm by inspecting
components).
Recondition piston, rings, cylinder bore, valves and
valves guides.
Restricted exhaust. Check exhaust screen/spark arrestor (if equipped). Clean
or replace as needed. Repair or replace any other
damaged/restricted muffl er or exhaust system parts.
CRANKCASE VACUUM TEST
WARNING
Carbon Monoxide can cause severe nausea,
fainting or death.
Avoid inhaling exhaust fumes. Never run
engine indoors or in enclosed spaces.
Engine exhaust gases contain poisonous carbon
monoxide. Carbon monoxide is odorless, colorless,
and can cause death if inhaled.
To test crankcase vacuum with manometer:
1. Insert rubber stopper into oil fi ll hole. Be sure pinch
clamp is installed on hose and use tapered adapters
to connect hose between stopper and one
manometer tube. Leave other tube open to
atmosphere. Check that water level in manometer is
at 0 line. Make sure pinch clamp is closed.
2. Start engine and run no-load high speed.
3. Open clamp and note water level in tube.
Level in engine side should be a minimum of
10.2 cm (4 in.) above level in open side.
If level in engine side is less than specifi ed (low/no
vacuum), or level in engine side is lower than level in
open side (pressure), check for conditions in table
below.
4. Close pinch clamp before stopping engine.
To test crankcase vacuum with vacuum/pressure gauge
(inches of water gauge only):
1. Remove dipstick or oil fi ll plug/cap.
2. Install adapter into oil fi ll//dipstick tube opening,
upside down over end of a small diameter dipstick
tube, or directly into engine if a tube is not used.
Insert barbed gauge fi tting into hole in stopper.
3. Run engine and observe gauge reading.
Analog tester–needle movement to left of 0 is a
vacuum, and movement to right indicates a pressure.
Digital tester–depress test button on top of tester.
Crankcase vacuum should be a minimum of 10.2 cm
(4 in.) of water. If reading is below specifi cation, or if
pressure is present, check table below for possible
causes and conclusions.
WARNING
Rotating Parts can cause severe injury.
Stay away while engine is in operation.
Keep hands, feet, hair, and clothing away from all
moving parts to prevent injury. Never operate engine
with covers, shrouds, or guards removed.
A partial vacuum should be present in crankcase when engine is operating. Pressure in crankcase (normally caused
by a clogged or improperly assembled breather) can cause oil to be forced out at oil seals, gaskets, or other available
spots.
Crankcase vacuum is best measured with either a water manometer or a vacuum gauge (inches of water gauge only).
Complete instructions are provided in kits.
1924 690 30 Rev. G KohlerEngines.com
Troubleshooting
COMPRESSION TEST
For Command Twins:
A compression test is best performed on a warm engine. Clean any dirt or debris away from base of spark plug(s)
before removing them. Be sure choke is off , and throttle is wide open during test. Compression should be at least 160
psi and should not vary more than 15% between cylinders.
All other models:
These engines are equipped with an automatic compression release (ACR) mechanism. It is diffi cult to obtain an
accurate compression reading because of ACR mechanism. As an alternative, use cylinder leakdown test described
below.
CYLINDER LEAKDOWN TEST
A cylinder leakdown test can be a valuable alternative to a compression test. By pressurizing combustion chamber
from an external air source you can determine if valves or rings are leaking, and how badly.
Cylinder leakdown tester is a relatively simple, inexpensive leakdown tester for small engines. This tester includes a
quick-connect for attaching adapter hose and a holding tool.
1. Run engine for 3-5 minutes to warm it up.
2. Remove spark plug(s) and air fi lter from engine.
3. Rotate crankshaft until piston (of cylinder being tested) is at top dead center (TDC) of compression stroke. Hold
engine in this position while testing. Holding tool supplied with tester can be used if PTO end of crankshaft is
accessible. Lock holding tool onto crankshaft. Install a 3/8 in. breaker bar into hole/slot of holding tool, so it is
perpendicular to both holding tool and crankshaft PTO.
If fl ywheel end is more accessible, use a breaker bar and socket on fl ywheel nut/screw to hold it in position. An
assistant may be needed to hold breaker bar during testing. If engine is mounted in a piece of equipment, it may
be possible to hold it by clamping or wedging a driven component. Just be certain that engine cannot rotate off of
TDC in either direction.
4. Install adapter into spark plug hole, but do not attach it to tester at this time.
5. Turn regulator knob completely counterclockwise.
6. Connect an air source of at least 50 psi to tester.
7. Turn regulator knob clockwise (increase direction) until gauge needle is in yellow set area at low end of scale.
8. Connect tester quick-connect to adapter hose. While fi rmly holding engine at TDC, gradually open tester valve.
Note gauge reading and listen for escaping air at combustion air intake, exhaust outlet, and crankcase breather.
Condition Conclusion
Air escaping from crankcase breather. Ring or cylinder worn.
Air escaping from exhaust system. Defective exhaust valve/improper seating.
Air escaping from intake. Defective intake valve/improper seating.
Gauge reading in low (green) zone. Piston rings and cylinder in good condition.
Gauge reading in moderate (yellow) zone. Engine is still usable, but there is some wear present.
Customer should start planning for overhaul or
replacement.
Gauge reading in high (red) zone. Rings and/or cylinder have considerable wear. Engine
should be reconditioned or replaced.
Air Cleaner/Intake
20 24 690 30 Rev. GKohlerEngines.com
AIR CLEANER
These systems are CARB/EPA certifi ed and components
should not be altered or modifi ed in any way.
Air Cleaner Components
B
E
F
H
A
C
D
G
A Air Cleaner Cover B Air Cleaner Knob
C Wing Nut D Element Cover
E Rubber Seal F Precleaner
G Paper Element H Air Cleaner Base
NOTE: Operating engine with loose or damaged air
cleaner components could cause premature
wear and failure. Replace all bent or damaged
components.
NOTE: Paper element cannot be blown out with
compressed air.
Loosen knob and remove air cleaner cover.
Precleaner
1. Remove precleaner from paper element.
2. Replace or wash precleaner in warm water with
detergent. Rinse and allow to air dry.
3. Saturate precleaner with new engine oil; squeeze
out excess oil.
4. Reinstall precleaner over paper element.
Paper Element
1. Clean area around element. Remove wing nut,
element cover, and paper element with precleaner.
2. Separate precleaner from element; service
precleaner and replace paper element.
3. Check condition of rubber seal and replace if
necessary.
4. Install new paper element on base; install precleaner
over paper element; reinstall element cover and
secure with wing nut.
Reinstall air cleaner cover and secure with knob.
BREATHER TUBE
Ensure sure both ends of breather tube are properly
connected.
AIR COOLING
WARNING
Hot Parts can cause severe burns.
Do not touch engine while operating or just
after stopping.
Never operate engine with heat shields or guards
removed.
Proper cooling is essential. To prevent over heating,
clean screens, cooling fi ns, and other external surfaces
of engine. Avoid spraying water at wiring harness or any
electrical components. Refer to Maintenance Schedule.
21
Fuel System
24 690 30 Rev. G KohlerEngines.com
External Fuel System Components
A
F
D
E
G
I
B
C
H
J
G
A Carburetor B Governor Lever C
Electronic Throttle
Control
D Hose Clamp
E Vacuum Line F Vaporizer G Fuel Line H Electric Lock-Off /Filter
I Regulator J Regulator Bracket
Typical LPG/NG fuel systems and related components
include:
● Fuel Tank (Liquid Withdrawal) (LPG only)
● Electric Lock-Off /Filter Assembly
● Vaporizer (LPG only)
● Regulator (Combination Primary/Secondary/Vacuum
Lock-Off )
● Carburetor
● High Pressure Fuel Line(s) (LPG only)
● Vacuum Line
LPG/NG fuel travels through fuel line to electric lock-off /
fi lter assembly. Lock-off opens internally when key switch
is turned ON, permitting fi ltered fuel to fl ow. A vaporizer
(LPG only) is mounted in fl ow of discharged cooling air.
It absorbs heat from cooling air and transfers it to fuel,
changing liquefi ed petroleum to a vapor or gaseous
state, while partially stepping down fuel pressure. Gas/
vapor fl ows under this decreased pressure to regulator
where it is further reduced to a usable, regulated
pressure. Regulator, activated by intake manifold
vacuum, controls fuel fl ow to carburetor. In venturi of
carburetor, fuel vapor is mixed with incoming air from air
cleaner in correct ratio for effi cient combustion.
FUEL RECOMMENDATIONS
Refer to Maintenance.
FUEL LINE
Low permeation fuel line must be installed on carbureted
Kohler Co. engines to maintain EPA and CARB
regulatory compliance.
22
Fuel System
KohlerEngines.com 24 690 30 Rev. G
IMPCO Carburetor Components
G
C
H
F
A
D
E
B
D
C
B
A Venturi B Fuel Inlet
C
Idle Speed
Adjustment Screw
D Throttle Lever
E
Venturi Retaining
Screw
F
Load Block
(if equipped)
G
Idle Speed Clamp
Bracket Mounting
Screw
H
Clamp Brackets
(if equipped)
Nikki Carburetor Components
G
B
A
D
E
I
C
H
F
A
Rear Plug with
Sealing Washer
B Fuel Inlet
C
Choke Lever
Assembly
D Throttle Lever
E Plastic Bushing F
Idle Speed
Adjustment Screw
G Vacuum Port H
Transfer Chamber
Cover
I
Choke Plate/Shaft
Assembly
WARNING
Explosive Fuel can cause fi res and severe
burns.
If a gaseous odor is detected, ventilate area
and contact an authorized service technician.
LPG is extremely fl ammable and is heavier than air
and tends to settle in low areas where a spark or fl ame
could ignite gas. Do not start or operate this engine
in a poorly ventilated area where leaking gas could
accumulate and endanger safety of persons in area.
NG is extremely fl ammable, is lighter than air, and
rises. Do not start or operate this engine in a poorly
ventilated area where leaking gas could accumulate
and endanger safety of persons in area.
To ensure personal safety, installation and repair of
LPG/NG fuel supply systems must be performed only
by qualifi ed LPG/NG system technicians. Improperly
installed and maintained LPG/NG equipment could
cause fuel supply system or other components to
malfunction, causing gas leaks.
Observe federal, state and local laws governing LPG/
NG fuel, storage, and systems.
23
Fuel System
24 690 30 Rev. G KohlerEngines.com
Condition Conclusion
Engine cranks but will not start. LPG fuel tank closed, low, or empty.
Lock-off not opening electrically, preventing fuel fl ow.
Fuel fi lter (located inside lock-off ) dirty or blocked.
Insuffi cient vacuum signal, regulator not opening.
● Vacuum line between carburetor and regulator cracked, leaking, kinked, or
pinched.
● Carburetor loose.
● Intake manifold loose or leaking.
● Excessive internal engine wear.
Faulty regulator.
● Primary valve not opening.
● Diaphragm spring adjustment incorrect.
● Idle adjustment screw incorrectly set.
● Vent(s) blocked/restricted.
Restricted/blocked fuel line.
Blocked carburetor fuel circuit.
Loose/leaking fuel enrichment hose (IMPCO carburetor system).
Hard starting, runs roughly, or
stalls at idle speed.
LPG fuel tank low.
Vacuum line between carburetor and regulator pinched, cracked, or leaking.
Carburetor idle speed set too low (should be at least 1200 RPM).
Carburetor idle circuit restricted.
Dirty/restricted air cleaner.
Dirty/restricted lock-off fi lter.
Frozen/malfunctioning regulator. Check/adjust primary pressure.
Excessive external load on engine.
Excessive internal wear.
Loose/leaking fuel enrichment hose (IMPCO carburetor system).
Irregular or inconsistent idle. Improper operation/adjustment of regulator, idle adjustment screw, throttle
opening, and/or engine governor.
Secondary valve in regulator not closing. Readjust idle screw (counterclockwise)
so valve can close fully against seat.
Loose/leaking vacuum line.
Loose carburetor mounting and/or line connections.
Damaged diaphragm(s) within regulator.
Debris in regulator. Flush debris from drain plug or remove regulator from system,
disassemble body and remove debris.
Dirt or debris in carburetor. Remove carburetor, disassemble and clean/service as
required. If venturi (IMPCO carburetor) removal is performed, mark its orientation
to carburetor body for proper reinstallation.
Loose/leaking fuel enrichment hose (IMPCO carburetor system).
TROUBLESHOOTING CHECKLIST
If engine starts hard, runs roughly, or stalls, check
following areas.
1. Make sure LPG fuel tank is fi lled and shut-off valve
is fully opened.
2. Make sure fuel is reaching carburetor.
3. Make sure air cleaner element and precleaner are
clean and all components are fastened securely.
4. Make sure ignition, governor, exhaust, throttle, and
choke control systems are all operating properly.
5. Check compression.
If engine continues to start hard, run roughly, or stall
after these checks have been made, use following
troubleshooting guide.
24
Fuel System
KohlerEngines.com 24 690 30 Rev. G
Condition Conclusion
Engine stalls during operation. No fuel.
Faulty lock-off or blocked fi lter.
Improper governor setting.
Damaged diaphragms within regulator.
Vacuum line leaking, loose, or pinched.
Restricted fuel line.
Loose/leaking fuel enrichment hose (IMPCO carburetor system).
Low power. Air cleaner or exhaust system dirty/restricted.
Low fuel.
Rich gas condition (fl ooding) through regulator.
● Dirty/restricted valves in regulator.
● Damaged primary diaphragm in regulator.
No fuel.
● Electric lock-off not opening, fi lter blocked, or restriction within fuel line.
● Leaking, loose, or cracked vacuum line from carburetor to regulator.
● Leaking, or loose intake system components.
● Regulator primary valve not opening.
● Secondary, or vacuum lock-off diaphragm within regulator leaking.
● Low pressure rubber hose kinked.
● Frozen regulator.
Improper ignition timing.
Loose/incorrect throttle lever/clamp bracket positioning.
Loose or incorrectly positioned high speed throttle plate stop.
Engine runs lean. Electrical problem causing intermittent lock-off operation, or lock-off is faulty.
Filter in lock-off dirty or restricted.
Restriction in fuel system.
Idle holes plugged; dirt in fuel delivery channels.
Carburetor fuel circuit restriction.
Loose/leaking fuel enrichment hose (IMPCO carburetor system).
High fuel consumption. Fuel leak. Check lines, connections, and system components for leaks with soapy
water. Fix any leaks immediately.
Incorrectly set regulator, or leakage from valves in regulator. Readjust, service, or
replace regulator as required.
Dirty air cleaner or precleaner.
Choke plate in carburetor not opening completely.
LPG/NG CARBURETOR ADJUSTMENTS
NOTE: Carburetor adjustments should be made only
after engine has warmed up.
NOTE: Actual low idle speed (RPM) depends on
application. Refer to equipment manufacturer’s
recommendations. Low idle speed for basic
engines is 1200 RPM.
LPG/NG carburetor and regulator are designed to deliver
correct fuel-to-air mixture to engine under all operating
conditions. High and low idle fuel mixture settings are
preset at factory, and cannot be adjusted. These engines
are equipped with an IMPCO or Nikki carburetor.
Although both carburetors function similarly, each is
unique and should not be interchanged.
Some IMPCO carburetors incorporate an external
load block assembly, which controls fi nal fuel fl ow to
carburetor for all throttle positions except idle. Calibrated
and fl ow-matched to carburetor, it functions similarly to
preset fuel mixture settings in other carburetors. Load
block assembly is not available separately, nor is any
internal servicing permitted or possible. If a problem is
encountered and determined to be caused by load block,
carburetor should be replaced.
LPG/NG FUEL SYSTEM COMPONENT SERVICE
LPG/NG Carburetor - Cleaning
Carburetor may be cleaned if necessary. Removal from
engine and limited disassembly will aid in cleaning.
25
Fuel System
24 690 30 Rev. G KohlerEngines.com
IMPCO Carburetor
NOTE: Do not loosen or alter mounted position of
clamping brackets and/or stop collar on throttle
shaft. Each is preset, in correlation to a specifi c
position of throttle plate (shaft), or acts as a stop.
None of these attached components, including
throttle plate or shaft, requires disassembly or
removal for any carburetor servicing. All
components on throttle shaft should be left
intact. If settings of any one of these is
inadvertently loosened or altered, each must be
checked/reset, or performance and operation
will be aff ected. Refer to procedure included in
reassembly/installation sequence to check or
reset.
1. Turn off fuel supply at tank.
2. Remove air cleaner, breather hose, fuel line, vacuum
hose, choke, and throttle linkages. Remove
mounting hardware, carburetor, and gaskets from
engine. Discard gaskets.
3. Carburetor venturi may be removed for inspection
and appropriate cleaning.
a. Remove screws securing air cleaner adapter and
gasket to carburetor.
b. Mark a small line on outer edge of venturi for
proper orientation and reinstallation later.
c. Loosen venturi retaining screw on side of
carburetor body and lift out venturi.
4. Inspect overall condition of fuel enrichment hose
attached to carburetor. It must be free of cracks,
deterioration, and damage. Disconnect fuel
enrichment hose from carburetor fi ttings to clean or
check condition as required. Replace with a new
Kohler high pressure hose (LP rated) if condition is
questionable in any way. Secure new hose using
new clamps.
5. Clean all parts as required, use a good carburetor
cleaner, following manufacturer's instructions. Blow
clean, compressed air through all passages. Do not
poke or probe into load block assembly as damage
can be done, resulting in serious operational
problems.
Nikki Carburetor
1. Turn off fuel supply.
2. Remove air cleaner, breather hose, fuel line, vacuum
hose, choke, and throttle linkages. Remove nuts,
carburetor, and gaskets from engine. Discard
gaskets.
3. Remove fuel transfer chamber cover by removing
screws. Carefully remove cover and gasket. Discard
gasket.
4. Main jet is fi xed and nonadjustable, but may be
accessed for cleaning by removing rear plug and
sealing washer. Discard washer.
5. In order to clean off -idle transfer passages and
carburetor thoroughly, use a good carburetor cleaner
and follow manufacturer's instructions. Blow clean,
compressed air through passages and make sure all
are open before reassembling. Do not use wire or
metal objects to clean passages or carburetor body.
LPG/NG Carburetor - Inspection
NOTE: Do not attempt to disassemble or remove either
shaft from carburetor body, including mounted
clamp brackets on IMPCO style carburetors.
Screws attaching choke and throttle plate to
their respective shafts are staked or bonded to
prevent loosening. Plate(s) and shaft(s) are not
available separately. If detrimental wear or
damage is found in any parts, carburetor should
be replaced.
1. Inspect carburetor body and removable venturi
(IMPCO carburetor) for cracks, holes, and other
wear or damage.
2. Check choke shaft (Nikki carburetor only) and
throttle shaft for wear and free movement.
LPG/NG Carburetor - Reassembly
IMPCO Carburetor
NOTE: Clamp brackets and stop collar mounted on
throttle shaft should still be in their original
positions, and not require any readjustment/
resetting. If mounted position of any one of these
was aff ected or changed, it will be necessary to
check and reset position of each before
proceeding. Follow Instructions for Checking/
Positioning Clamp Brackets Mounted on Throttle
Shaft, then continue with steps 6 and 7.
1. Slide venturi into carburetor body, aligning position
mark made prior to removal. Correctly installed,
discharge holes should not be visible from top.
2. Secure with venturi retaining screw. Torque screw to
4.0 N·m (36 in. lb.).
3. Install a new adapter gasket and mount air cleaner
adapter onto carburetor with screws. Torque screws
to 4.0 N·m (36 in. lb.).
4. Install a new carburetor gasket onto intake manifold
adapter, followed by carburetor. Install and fi nger
tighten mounting fasteners.
5. Connect Z end of throttle linkage and dampening
spring to throttle clamp bracket on throttle shaft.
Attach opposite end of linkage and spring to
governor lever.
6. Manually move governor lever toward carburetor as
far as it will go.
7. Check that throttle plate is now fully open or
reposition carburetor slightly on mounting hardware
so it is fully open. Torque mounting screws or nuts to
6.2-7.3 N·m (55-65 in. lb.).
Nikki Carburetor
NOTE: If additional adjustment is required, loosen
throttle linkage clamp bracket mounting screw,
set throttle shaft to full throttle position against
head of stop screw, and retighten clamp
mounting screw securely.
1. Reinstall rear plug with a new sealing washer.
Tighten plug securely.
2. Reinstall fuel transfer chamber cover with a new
gasket. Secure with screws.
26
Fuel System
KohlerEngines.com 24 690 30 Rev. G
3. Install new carburetor mounting gasket on manifold
studs, followed by carburetor and new air cleaner
base gasket.
4. Reconnect throttle and choke linkages, and fuel and
vacuum lines.
5. Reinstall air cleaner base and breather tube. Secure
base with mounting nuts. Torque nuts to 9.9 N·m (88
in. lb.). Install rest of air cleaner system.
6. Check to be sure all system connections are tight.
7. Reset idle RPM and recheck high idle (governed
speed) after starting and allowing suffi cient warm-up
time.
Instructions for Checking/Positioning Clamp
Brackets Mounted on Throttle Shaft
Use only if position or mounting of clamp bracket(s) has
been disturbed.
Idle Speed Clamp Bracket Position
1. Counting number of turns, back idle speed
adjustment screw off (counterclockwise), so only 1 to
1 1/2 threads are visible.
2. Loosen clamp bracket mounting screw, and pivot
throttle shaft to fully close throttle plate.
3. Hold throttle plate closed and rotate clamp bracket
until end of screw contacts stop. Insert a 0.025 mm
(0.001 in.) feeler gauge between carburetor housing
and side of clamp bracket to set endplay, then
tighten mounting screw securely.
4. Reset idle speed adjustment screw back to original
position.
High Speed/Stop Collar Position
NOTE: After idle speed clamp bracket and high speed
stop collar positions have been set, check that
throttle shaft pivots freely without binding or
restriction.
1. Make sure idle speed clamp position has already
been checked or properly set.
2. Rotate and hold throttle shaft so throttle plate is fully
open/perfectly vertical.
3. Insert a 0.025 mm (0.001 in.) feeler gauge between
side of stop collar and carburetor housing, then
check or set position of stop collar. Head of
mounting screw must be in contact with carburetor
boss from back (hose/fi tting) side, preventing any
further rotation over center. Set or adjust stop collar
as required.
4. Tighten screw securely.
Throttle Linkage Clamp Bracket Position
Carburetor must be assembled to engine with linkage
attached to set this position.
1. Throttle linkage clamp bracket should be positioned
on idle speed clamp bracket side of throttle shaft.
2. Manually move governor lever, with throttle linkage
connected, toward carburetor as far as it will go.
Hold it in this position.
3. Looking down throat of carburetor, check that throttle
plate is in full throttle position and that head of high
speed collar stop screw is in contact with carburetor
boss. If not, loosen carburetor mounting hardware
and reposition carburetor slightly. Torque carburetor
mounting screws or nuts to 6.2-7.3 N·m (55-65 in.
lb.).
HIGH ALTITUDE OPERATION
Standard carburetor calibrations will provide proper
operation up to altitudes of 1500 m (5000 ft.). No internal
changes are necessary or available for either carburetor.
Idle Speed Adjustment
1. Start engine and run at half throttle for 5 to 10
minutes. Check that throttle and choke (Nikki
carburetor) plates can open fully.
2. Place throttle control into idle or slow position. Turn
low idle speed adjusting screw in or out, to obtain a
low idle speed of 1200 RPM (± 75 RPM), or set to
application specifi cations. Check speed using a
tachometer.
ELECTRIC LOCK-OFF/FILTER ASSEMBLY
Electric Lock-off /Filter Components
B
C
A
A Inlet Fitting B Filter
C Outlet Fitting
Functional Test
Electric lock-off can be easily tested to verify that it is
functional. Remove it from system for testing. Using a
12 volt power supply or battery, connect one wire lead to
positive (+) lead of power supply, and touch remaining
wire lead to negative (–) lead of power supply. When
connection is made, an audible click should be heard
indicating opening of lock-off . While energized, blow
compressed air through it to determine if it is blocked or
restricted.
Filter Service
Filter inside lock-off assembly should be replaced.
Cleaning of fi lter element is not recommended. Order
a replacement fi lter element by appropriate Kohler part
number.
27
Fuel System
24 690 30 Rev. G KohlerEngines.com
VAPORIZER ASSEMBLY
Vaporizer Components
B
C
A
A Vaporizer B Fitting
C Elbow
Outer surface of vaporizer should be kept free of dirt
and debris accumulation, which will cause a loss of
vaporization effi ciency. Visual inspection and necessary
cleaning should be performed on a regular basis, more
frequently under dusty or dirty conditions.
LPG/NG REGULATOR
Regulator controls both pressure and fl ow of fuel within
LPG/NG system. It is comprised of both a primary and
secondary chamber, which are dependent upon one
another. Two diff erent styles of regulators are used,
based upon system involved. Although basic design
and operating principles are similar, due to system
diff erences regulators should not be interchanged.
Following are separate sections covering theory of
operation and general service information for each style
of regulator. Detailed service/repair instructions are
included in rebuild kit for each regulator.
IMPCO (Beam) Regulator
Details and Components
BB
AA
X
Z
Y
W
V
U
T
R
P
Q
M
K
J
L
I
H
F
G
E
D
D
C
B
A
NO
S
A Expansion Plug B Adjustment Screw
C Secondary Pivot Pin D Pan Head Screw
E
Secondary Lever
Assembly
F Floor
G Vacuum Lock Spring H Bumper
I
Secondary
Diaphragm
J Vacuum Chamber
K
Vacuum Lock
Diaphragm Assembly
L Secondary Area
M
Torx Head Screw with
Split Lock Washer
N LPG/NG Entrance
O LPG/NG Passage P Primary Pivot Pin
Q Fillister Head Screw R
Primary Lever
Assembly
S Expansion Plug T Primary Spring
U
Secondary
Diaphragm Spring
V
Primary Diaphragm
Assembly
W LPG/NG Primary Area X Diaphragm Gasket
Y
Secondary Lever
Spring
Z
Passage to
Secondary Valve
AA Secondary Valve BB 1/8-27 NPT Plug
28
Fuel System
KohlerEngines.com 24 690 30 Rev. G
LPG/NG vapor enters regulator, then passes into primary
area, where pressure is reduced from up to 1724 kPa
(250 psi) at tank to 31 kPa (4.5 psi). Fuel pressure
against diaphragm overcomes spring and as movement
increases, spring will close lever. Primary diaphragm
breather is vented to secondary chamber so that rupture
of this diaphragm would direct fuel into carburetor.
Fuel now moves through passage, past secondary valve
into secondary area. As negative pressure (vacuum) is
created at carburetor venturi and is transmitted through
dry-gas hose to chamber secondary diaphragm is drawn
down and contacts secondary lever. Fuel will fl ow in
proportion to air velocity through carburetor venturi,
ensuring an ideal mixture at all engine speeds.
Whenever engine is operating, vacuum diaphragm is
down against fl oor and spring is compressed. Idle and
starting adjustment is made with a tamper-resistant
screw which regulates whisker wire system, opening
up secondary orifi ce slightly (but only when vacuum
diaphragm is drawn down). Very little vacuum is needed
to start this vacuum diaphragm travel: 0.2 in. Mercury
to start and 0.5 in. Mercury for full travel. When engine
stops rotating, loss of vacuum in section releases
diaphragm causing bumper to push against secondary
lever, overcoming action of whisker wire and ensuring
100% lock-off .
This patented Beam design will lock off primary
pressures up to fi ve times in excess of normal and
permits starting without priming or choking.
Nikki Regulator
Primary Chamber Details and Components
J
B
G
D
A
I
E
F
C
H
K
A Primary Valve B Primary Valve Seat
C Primary Chamber D Primary Diaphragm
E
Primary Diaphragm
Spring Adjustment
F Contact Button
G Primary Valve Lever H Primary Lever Spring
I Primary Pressure J Fuel Inlet
K
To Secondary
Chamber
Primary chamber reduces high pressure fuel fl ow from
tank and vaporizer down to approximately 29 kPa (4 psi).
Fuel fl owing from vaporizer enters inlet of regulator
under approximately 76 kPa (11 psi) of pressure. There
it is delivered to primary chamber through clearance
between primary valve and valve seat. As fuel continues
to fl ow and primary chamber approaches 29 kPa (4 psi),
primary diaphragm overcomes tension of diaphragm
spring. As diaphragm and contact button move up,
primary lever spring pushes primary lever up, in turn
closing primary valve and stopping fl ow of fuel. As fuel
is consumed and pressure in primary chamber drops
below 29 kPa (4 psi), diaphragm spring tension will be
greater than fuel pressure, causing primary diaphragm
to be pushed down. This causes contact button, to push
primary lever down, in turn opening primary valve and
admitting more fuel. In this manner, pressure within
primary chamber is maintained at a relatively constant
29 kPa (4 psi).
Secondary Chamber Details and Components
B
G
D
A
I
E
F
C
H
L
K
J
A Secondary Valve B Secondary Valve Seat
C Secondary Chamber D
Secondary
Diaphragm
E
Secondary
Diaphragm Spring
F
Secondary Valve
Lever
G
Vacuum Lock-off
Diaphragm
H Idle Adjust Screw
I Balance Spring J
From Primary
Chamber
K To Intake Manifold L To Carburetor
Secondary chamber further reduces fuel pressure from
29 kPa (4 psi) of primary chamber to near 0 kPa (0 psi)
pressure, to prevent excessive fuel fl ow to carburetor.
Fuel enters secondary chamber through clearance
between secondary valve and valve seat. While engine
is operating, and fuel is being drawn from secondary
chamber, secondary diaphragm is raised by atmospheric
pressure, simultaneously lifting secondary valve lever,
opening secondary valve, allowing fuel to fl ow. When
engine is running at idle, there may not be enough
vacuum created in carburetor venturi to overcome
tension of secondary diaphragm spring, and secondary
diaphragm cannot open valve. Under those conditions,
idle adjusting screw, and balance spring are used to
apply just enough pressure on diaphragm to maintain
suffi cient fuel fl ow for idle operation.
29
Fuel System
24 690 30 Rev. G KohlerEngines.com
Vacuum lock-off mechanism is located in secondary
chamber. When engine is running, manifold vacuum
above diaphragm draws it up, so secondary valve can
function normally. When engine is stopped, manifold
vacuum is terminated, and diaphragm relaxes and
pushes down on secondary valve lever, preventing any
fuel fl ow or leakage through regulator.
Preventative Maintenance
Regulator is preset at factory and generally requires no
further adjustment. No periodic service is required. Over
time, depending on fuel quality, operating environment,
and system performance, fuel deposits can accumulate
inside regulator. For Nikki regulators, perform following
steps to remove any accumulated deposits.
1. Turn supply valve off , run engine out of fuel, and turn
off ignition switch.
2. Disconnect and ground spark plug leads.
3. Remove 1/8 in. pipe plug from bottom of regulator
and drain any accumulated deposits.
4. Reinstall plug using pipe sealant with Tefl on
®
(Loctite
®
PST
®
592™ Thread Sealant or equivalent)
on threads and tighten securely. If required, a
replacement plug can be found at
KohlerEngine.com.
Regulator Service
It is recommended that disassembly, cleaning, and
resetting of regulator be performed using regulator
rebuilding kit available at KohlerEngine.com. Specifi c
instructions are included in rebuilding kit. Perform
regulator service following instructions provided. As all
adjustments and settings must be reset using specifi c
test equipment, this must be performed by qualifi ed
LPG/NG personnel only.
Governor System
30 24 690 30 Rev. GKohlerEngines.com
GOVERNOR
These engines are equipped with an electronic governor or a mechanical governor.
Governor Components
M
L
N
O
B
P
S
R
Q
I
K
J
H
Inside Engine
D
B
C
A
F
E
G
A Throttle Lever B Throttle Linkage C Governor Lever D Choke Linkage
E Governor Spring F Governed Idle Spring G Control Bracket H Regulating Pin
I Governor Gear J
Locking Tab Thrust
Washer
K Governor Gear Shaft L Idle Solenoid
M
Electronic Governor
Assembly
N
Digital Linear
Actuator (DLA)
O DLA Bracket P Linkage Spring
Q
Linkage Retaining
Bushing
R
Throttle Lever
Adapter
S
Governor Control
Unit (GCU)
Mechanical Governor
Engine is equipped with a centrifugal fl yweight
mechanical governor. It is designed to hold engine speed
constant under changing load conditions. Governor gear/
fl yweight mechanism is mounted inside crankcase on
closure plate, and is driven off gear on camshaft.
This governor design works as follows:
● Centrifugal force acting on rotating governor gear
assembly causes fl yweights to move outward as
speed increases. Governor spring tension moves
them inward as speed decreases.
● As fl yweights move outward, they cause regulating pin
to move outward.
● Regulating pin contacts tab on cross shaft causing
shaft to rotate. One end of cross shaft protrudes
through crankcase. Rotating action of cross shaft is
transmitted to throttle lever of carburetor through
external linkage.
● When engine is at rest, and throttle is in FAST
position, tension of governor spring holds throttle plate
open. When engine is operating, governor gear
assembly is rotating. Force applied by regulating pin
against cross shaft tends to close throttle plate.
Governor spring tension and force applied by
regulating pin balance each other during operation, to
maintain engine speed.
● When load is applied and engine speed and governor
gear speed decreases, governor spring tension moves
governor lever to open throttle plate wider. This allows
more fuel into engine, increasing engine speed. As
speed reaches governed setting, governor spring
tension and force applied by regulating pin will again
off set each other to hold a steady engine speed.
Governor Adjustments
NOTE: Do not tamper with governor setting. Overspeed
is hazardous and could cause personal injury.
Initial Adjustment Procedure
Make this adjustment whenever governor arm is
loosened or removed from cross shaft. Adjust as follows:
1. Make sure throttle linkage is connected to governor
arm and throttle lever on carburetor.
2. Loosen nut holding governor lever to cross shaft.
3. Move governor lever toward carburetor as far as it
will go (wide open throttle) and hold in this position.
Governor System
3124 690 30 Rev. G KohlerEngines.com
4. Insert a long thin rod or tool into hole on cross shaft
and rotate shaft counterclockwise (viewed from end)
as far as it will turn, then torque nut to 6.8 N·m
(60 in. lb.).
Sensitivity Adjustment
Governor sensitivity is adjusted by repositioning
governor spring in holes of governor lever. If speed
surging occurs with a change in engine load, governor
is set too sensitive. If a big drop in speed occurs when
normal load is applied, governor should be set for
greater sensitivity and adjust as follows:
1. To increase sensitivity, move spring closer to
governor cross shaft.
2. To decrease sensitivity, move spring away from
governor cross shaft.
ELECTRONIC GOVERNOR
Two types of electronic governor have been used. One
has an electronic governor assembly (rotary stepper
motor) that secures near carburetor, with a throttle
linkage that connects these two components. Other type
has a digital linear actuator and governor control unit as
explained below.
Electronic governor regulates engine speed at varying
loads. Typical electronic governor includes:
● Digital linear actuator.
● Throttle linkage.
● Linkage spring.
● Choke linkage.
● Throttle lever adapter.
● Governor Control Unit.
Digital Linear Actuator (DLA)
Energizing bi-directional digital linear actuator coils in
proper sequence, causes threaded shaft to move out
of, or back into rotor, in precise linear increments. When
power is removed, actuator shaft remains in position.
DLA must initialize (fully extend) to move throttle plate to
closed position, and partially open for starting. Correct
adjustment of DLA is critical to achieve full range of
throttle plate movement. See Adjustment.
Governor control unit (GCU) senses engine speed
by pulse voltage inputs from ignition modules. GCU
regulates engine speed by variable input voltage from a
customer-supplied potentiometer or a single pole, single
throw (SPST) switch.
NOTE: Actual speeds depend on application. Refer to
equipment manufacturer’s recommendations.
Potentiometer Specifi cations
Wiper Voltage Engine Speed (RPM)
0-1 Low Speed Endpoint
1-9 Variable Speed Endpoint
9-16 High Speed Endpoint
SPST Switch Specifi cations
Switch Position Engine Speed (RPM)
Open Low Speed Endpoint
Closed High Speed Endpoint
GCU Safety Features
In event of an engine overspeed condition, GCU will shut
down engine by grounding ignition modules.
GCU will shut down engine by grounding ignition when
power to GCU is lost.
Linkage
Throttle linkage spring will fully open throttle plate if
linkage becomes detached from DLA. This will create an
overspeed condition causing engine to shut down. DLA
shaft will have to be manually screwed back into body,
and then retracted before reassembling linkage.
Adjustment
DLA must be in fully retracted position during assembly.
Full range of throttle plate movement will not be
achieved if DLA is partially extended when assembled.
Loosen DLA mounting plate screws located on top of
actuator plate. With throttle linkage centered in U-Clip
or secured with a retaining clip at end of DLA shaft,
slide DLA bracket assembly back until throttle plate is
fully open. Torque mounting plate screws to 2.5 N·m
(22 in. lb.).
Troubleshooting
Engine Starts But Will Not Continue to Run
1. Check linkage connection between DLA and throttle
plate.
2. Verify DLA initializes when power is supplied (key
switch in start or run position).
3. Test potentiometer wiper output voltage (if
equipped).
4. Test SPST switch (if equipped).
5. Check wire harness and connections.
Engine Does Not Run At Expected Speed
1. Check to see that throttle linkage and DLA have full
range of motion having no mechanical interference.
2. Test potentiometer wiper voltage (if equipped).
3. Test SPST switch (if equipped).
Lubrication System
32 24 690 30 Rev. GKohlerEngines.com
This engine uses a full pressure lubrication system which
delivers oil under pressure to crankshaft, camshaft,
connecting rod bearing surfaces, and hydraulic valve
lifters.
A high-effi ciency gerotor oil pump maintains high oil fl ow
and oil pressure, even at low speeds and high operating
temperatures. A pressure relief valve limits maximum
pressure of system. Closure plate must be removed to
service oil pickup, pressure relief valve, and oil pump.
Lubrication Components
H
E
F
D
B
A
C
G
A Press-In Dipstick B Thread-On Dipstick
C Oil Sentry
™
D Oil Fill Cap
E Oil Cooler F Oil Filter
G Oil Drain Plug H Back Side
OIL RECOMMENDATIONS
Refer to Maintenance.
CHECK OIL LEVEL
NOTE: To prevent extensive engine wear or damage,
never run engine with oil level below or above
operating range indicator on dipstick.
Ensure engine is cool. Clean oil fi ll/dipstick areas of any
debris.
1. Remove dipstick; wipe oil off .
a. Press-in cap: reinsert dipstick into tube; press
completely down.
or
b. Thread-on cap: reinsert dipstick into tube; rest
cap on tube, do not thread cap onto tube.
2. Remove dipstick; check oil level. Level should be at
top of indicator on dipstick.
3. If oil is low on indicator, add oil up to top of indicator
mark.
4. Reinstall dipstick and tighten securely.
CHANGE OIL AND FILTER
Change oil while engine is warm.
1. Clean area around oil fi ll cap/dipstick, drain plug/oil
drain valve.
a. Remove drain plug and oil fi ll cap/dipstick. Allow
oil to drain completely.
or
b. Open oil drain valve cap; if needed, attach a
length of 1/2 in. I.D. hose to direct oil into
appropriate container; twist valve drain body
counterclockwise and pull. Remove dipstick.
Allow oil to drain completely.
2. Clean area around oil fi lter. Place a container under
fi lter to catch any oil and remove fi lter. Wipe off
mounting surface.
a. Reinstall drain plug. Torque to 13.6 N·m
(10 ft. lb.).
or
b. Close oil drain valve body, remove hose (if used),
and replace cap.
3. Place new fi lter in shallow pan with open end up. Fill
with new oil until oil reaches bottom of threads. Allow
2 minutes for oil to be absorbed by fi lter material.
4. Apply a thin fi lm of clean oil to rubber gasket on new
fi lter.
5. Refer to instructions on oil fi lter for proper
installation.
6. Fill crankcase with new oil. Level should be at top of
indicator on dipstick.
7. Reinstall oil fi ll cap/dipstick and tighten securely.
8. Start engine; check for oil leaks. Stop engine; correct
leaks. Recheck oil level.
9. Dispose of used oil and fi lter in accordance with
local ordinances.
OIL COOLER (if equipped)
Blower Housing Mounted Oil Cooler
1. Clean fi ns with a brush or compressed air.
2. Remove screws securing oil cooler and tilt to clean
back side.
3. Reinstall oil cooler.
Crankcase Mounted Oil Cooler
Clean fi ns with a brush or compressed air.
Lubrication System
3324 690 30 Rev. G KohlerEngines.com
OIL SENTRY
™
(if equipped)
This switch is designed to prevent engine from starting
in a low oil or no oil condition. Oil Sentry
™
may not shut
down a running engine before damage occurs. In some
applications this switch may activate a warning signal.
Read your equipment manuals for more information.
Oil Sentry
™
pressure switch is installed in breather cover.
On engines not equipped with Oil Sentry
™
installation
hole is sealed with a 1/8-27 N.P.T.F. pipe plug.
Installation
1. Apply pipe sealant with Tefl on
®
(Loctite
®
PST
®
592™
Thread Sealant or equivalent) to threads of switch.
2. Install switch into tapped hole in breather cover.
3. Torque switch to 4.5 N·m (40 in. lb.).
Testing
Compressed air, a pressure regulator, pressure gauge,
and a continuity tester are required to test switch.
1. Connect continuity tester across blade terminal and
metal case of switch. With 0 psi pressure applied to
switch, tester should indicate continuity (switch
closed).
2. Gradually increase pressure to switch. As pressure
increases through range of 3-5 psi tester should
indicate a change to no continuity (switch open).
Switch should remain open as pressure is increased
to 90 psi maximum.
3. Gradually decrease pressure through range of 3-5
psi. Tester should indicate a change to continuity
(switch closed) down to 0 psi.
4. Replace switch if it does not operate as specifi ed.
Electrical System
34 24 690 30 Rev. GKohlerEngines.com
SPARK PLUGS
CAUTION
Electrical Shock can cause injury.
Do not touch wires while engine is running.
Spark Plug Component and Details
B
A
C
D
A Wire Gauge B Spark Plug
C Ground Electrode D Gap
NOTE: Do not clean spark plug in a machine using
abrasive grit. Some grit could remain in spark
plug and enter engine causing extensive wear
and damage.
Engine misfi re or starting problems are often caused
by a spark plug that has improper gap or is in poor
condition.
Engine is equipped with following spark plugs:
Gap 0.76 mm (0.030 in.) all except NG
CD Fixed
0.51 mm (0.020 in.) NG CD Fixed
Thread Size 14 mm
Reach 19.1 mm (3/4 in.)
Hex Size 15.9 mm (5/8 in.)
Refer to Maintenance for Repairs/Service Parts.
Service
Clean out spark plug recess. Remove plug and replace.
1. Check gap using wire feeler gauge. Adjust gap to
0.76 mm (0.030 in.) for all except NG with CD fi xed
timing or 0.51 mm (0.020 in.) for NG with CD fi xed
timing.
2. Install plug into cylinder head.
3. Torque plug to 27 N·m (20 ft. lb.).
Inspection
Inspect each spark plug as it is removed from cylinder
head. Deposits on tip are an indication of general
condition of piston rings, valves, and carburetor.
Normal and fouled plugs are shown in following photos:
Normal
Plug taken from an engine operating under normal
conditions will have light tan or gray colored deposits. If
center electrode is not worn, plug can be set to proper
gap and reused.
Worn
On a worn plug, center electrode will be rounded and
gap will be greater than specifi ed gap. Replace a worn
spark plug immediately.
Wet Fouled
A wet plug is caused by excess fuel or oil in combustion
chamber. Excess fuel could be caused by a restricted air
cleaner, a carburetor problem, or operating engine with
too much choke. Oil in combustion chamber is usually
caused by a restricted air cleaner, a breather problem,
worn piston rings, or valve guides.
3524 690 30 Rev. G KohlerEngines.com
Electrical System
Carbon Fouled
Soft, sooty, black deposits indicate incomplete
combustion caused by a restricted air cleaner, over rich
carburetion, weak ignition, or poor compression.
Overheated
Chalky, white deposits indicate very high combustion
temperatures. This condition is usually accompanied
by excessive gap erosion. Lean carburetor settings,
an intake air leak, or incorrect spark timing are normal
causes for high combustion temperatures.
BATTERY
A 12-volt battery with 400 cold cranking amps (cca) is
generally recommended for starting in all conditions. A
smaller capacity battery is often suffi cient if an
application is started only in warmer temperatures. Refer
to following table for minimum capacities based on
anticipated ambient temperatures. Actual cold cranking
requirement depends on engine size, application, and
starting temperatures. Cranking requirements increase
as temperatures decrease and battery capacity shrinks.
Refer to equipment's operating instructions for specifi c
battery requirements.
Battery Size Recommendations
Temperature Battery Required
Above 32°F (0°C) 200 cca minimum
0°F to 32°F (-18°C to 0°C) 250 cca minimum
-5°F to 0°F (-21°C to -18°C) 300 cca minimum
-10°F (-23°C) or below 400 cca minimum
If battery charge is insuffi cient to turn over engine,
recharge battery.
Battery Maintenance
Regular maintenance is necessary to prolong battery
life.
Battery Test
To test battery, follow manufacturer's instructions.
ELECTRONIC IGNITION SYSTEMS
Ignition System Components
A
Kill Switch/
Off Position of
Key Switch
B Air Gap
C Flywheel D Magnet
E Spark Plug F Ignition Modules
A
B
C
D
E
F
There are 3 diff erent types of ignition systems used on
these engines. All systems use an ignition module which
energizes spark plug. Diff erence in systems is in way
ignition timing is triggered.
All ignition systems are designed to be trouble free for
life of engine. Other than periodically checking/replacing
spark plugs, no maintenance or timing adjustments
are necessary or possible. Mechanical systems do
occasionally fail or break down. Refer to Troubleshooting
to determine root of a reported problem.
Reported ignition problems are most often due to poor
connections. Before beginning test procedure, check
all external wiring. Be certain all ignition-related wires
are connected, including spark plug leads. Be certain all
terminal connections fi t snugly. Make sure ignition switch
is in run position.
Electrical System
36 24 690 30 Rev. GKohlerEngines.com
W
C
H
D
B
I
A
AD
E
G
F
F
A
K
B
L
J
N
M
P
O
R
Q
S
T
U
V
R
W
R
X
Y
Z
V
AA
AB
AC
AF
AI
AJ
AL
AE
AK
AH
AG
R
T
V
V
AM
AN
AO
AH
Wiring Diagram-15/20/25 Amp Regulated Battery Charging System with Fixed Timing
3724 690 30 Rev. G KohlerEngines.com
Electrical System
Fixed Ignition System
This system uses a capacitive discharge (CD) coil. Ignition timing and spark remains constant regardless of engine
speed. Timing of spark is controlled by location of fl ywheel magnet group as referenced to engine TDC. A typical fi xed
ignition system consists of:
● 1 magnet assembly which is permanently affi xed to fl ywheel.
● 2 electronic capacitive-discharge ignition modules which mount on engine crankcase.
● 1 kill switch (or key switch) which grounds modules to stop engine.
● 2 spark plugs.
A Spark Plug(s) B Oil Pressure Switch C Oil Sentry
™
(Green) D White Kill
E
Flywheel Stator
Assembly
F Ignition Module G
Non-Smart Spark
™
Ignition
H
Rectifi er-Regulator
Connector
I Rectifi er-Regulator J Oil Sentry
™
Kill (Green) K Violet B+ L
Solenoid Shift Starter
Assembly
M Starter Solenoid Tang N Starter Solenoid Stud O Fuse P Blue
Q
Alternate Ignition Kill
(–)
R White S Accessory Terminal (+) T Yellow
U Ignition Kill V Red W Carburetor X Carburetor Solenoid
Y Black (Ground) Z Intake Manifold Screw AA Black AB
Oil Sentry
™
Panel
Light/Remote Light
AC Oil Sentry
™
Light AD Connector AE Magneto AF Key Switch
AG Accessory AH Battery AI Starter AJ Ground
AK Key Switch Ground AL Rectifi er AM Blue/Red AN Battery Positive
AO Battery Negative
Electrical System
38 24 690 30 Rev. GKohlerEngines.com
B
A
C
N
Q
A
O
R
Z
I
X
M
L
K J
J
AA
W
AB
AC
AR
P
AQ
AP
AS
AN
AO
AH
S
K
T
U
T
T
V
W
W
Y
W
AP
AM
F
H
F
C
D
E
G
D
E
AD
AK
AE
AF
AG
AH
AI
AJ
AL
K
W
T
W
Wiring Diagram-15/20/25 Amp Regulated Battery Charging System with Variable Ignition Timing SMART-
SPARK
™
K
AT
AT
3924 690 30 Rev. G KohlerEngines.com
Electrical System
Smart-Spark
™
Advance Ignition System
SMART-SPARK
™
equipped engines utilize an electronic capacitive discharge ignition system with electronic spark
advance. A typical application consists of following components:
● 1 magnet assembly which is permanently affi xed to fl ywheel.
● 2 electronic capacitive discharge ignition modules which mount on engine crankcase.
● 1 spark advance module which mounts to engine shrouding.
● 1 12 volt battery which supplies current to spark advance module.
● 1 kill switch (or key switch) which grounds spark advance module to stop engine.
● 2 spark plugs.
A Oil Pressure Switch B Oil Sentry
™
(Green) C Spark Plug(s) D Kill
E Trigger F Ignition Module G
Flywheel Stator
Assembly
H
22, 25 HP Smart-
Spark
™
Ignition
I
Module Speed
Advance 22, 25 HP
J Brown K Yellow L
Yellow on Analog
SAMs Pink on Digital
SAMs
M
Rectifi er-Regulator
Connector
N Rectifi er-Regulator O Oil Sentry
™
Kill (Green) P
Solenoid Shift Starter
Assembly
Q Violet (B+) R
Alternate Ignition Kill
(–)
S Accessory Terminal (+) T White
U Ignition Kill V Smart-Spark
™
W Red X Carburetor
Y Solenoid Lead Z Intake Manifold Screw AA Black AB
Oil Sentry
™
Panel
Light/Remote Light
AC Oil Sentry
™
Light AD Connector AE Magneto AF Key Switch
AG Accessory AH Battery AI Starter AJ Ground
AK Key Switch Ground AL Rectifi er AM Blue/Red AN Battery Positive
AO Battery Negative AP Blue AQ Fuse AR Starter Solenoid Stud
AS Starter Solenoid Tang AT Black (Ground)
Electrical System
40 24 690 30 Rev. GKohlerEngines.com
A
E
L
D
C
E
F
D
G
G
M
H
F
K
J
I
H
I
M
J
R
V
W
B
U
X
Z
AA
AB
AC
AE
AF
AG
D
F
AH
AI
AJ
AL
AM
AK
AQ
AN
AE
AP
AR
F
Z
E
F
AT
AN
AS
U
X
AU
AV
P
O
N
R
T
Y
E
Z
S
Q
A
F
E
AD
F
Wiring Diagram-15/20/25 Amp Regulated Battery Charging System with DSAI Ignition and Key Switch
4124 690 30 Rev. G KohlerEngines.com
Electrical System
Digital Spark Advance Ignition (DSAI) System
This system uses a digital microprocessor which is located in ignition modules. Ignition timing varies depending upon
engine speed with this system. There are 2 inductive-style ignition modules that control ignition timing based on
engine RPM. A typical DSAI application consists of:
● 1 magnet assembly, which is permanently affi xed to fl ywheel.
● 2 inductive, 12-volt ignition modules, which mount on engine crankcase.
● 1 12-volt battery, which supplies current to ignition modules.
● 1 kill switch (or key switch) which grounds spark advance module to stop engine.
● 2 spark plugs.
A Oil Pressure Switch B
Green (Oil Sentry
™
Pulse Signal Lead)
C
Black (Ground) Intake
Manifold Mounting
Screw
D Black
E White F Red G Spark Plug(s) H Black (Ground)
I Red (B+) J White (DSAI Kill) K Module Screw L
Flywheel Stator
Assembly
M DSAI Module N
White (AC Charging
Leads)
O
Rectifi er-Regulator
Connector
P Rectifi er-Regulator
Q Violet (B+ Lead) R Starter Assembly S
Oil Sentry
™
Pulse
Signal
T
Alternate Ignition
Pulse Signal (–)
U Fuse V Starter Solenoid Tang W Starter Solenoid Stud X Blue
Y
Accessory Terminal
(+)
Z Yellow AA Red (DSAI Power) AB White (DSAI Kill)
AC Carburetor AD Solenoid Lead AE Ground AF
Intake Manifold
Screw
AG Black (Ground) AH
Oil Sentry
™
Panel
Light/Remote Light
AI Oil Sentry
™
Light AJ Connector
AK Magneto AL Key Switch AM Accessory AN Battery
AO Starter AP
Key Switch Ground
(Black)
AQ Rectifi er AR Blue/Red
AS Battery Positive AT Battery Negative AU
Customer Supplied
Relay Cranking
AV Relay Stud
Electrical System
42 24 690 30 Rev. GKohlerEngines.com
Wiring Diagram-3 Amp Unregulated Battery Charging System/70 Watt Lighting
K
C
B
L
F
H
A
J
G
O
S
N
D
M
T
I
E
P
S
R
Q
A
R
S
B
A
Optional Oil
Sentry
™
Switch
(Shutdown)
B 12 V. Battery C
Optional Oil
Sentry
™
Switch
(Indicator Light)
D Light E
Ground-To-Kill
Lead (White)
F Ground G
Optional
Ammeter
H Optional Fuse I Key Switch J Red
K Blue L Solenoid M Lights N Starter O Yellow
P Diode Q
3 Amp/70 Watt
Flywheel Stator
R Black S Spark Plug(s) T Ignition Modules
Electronic Ignition Systems Tests
NOTE: Ignition tester must be used to test ignition on these engines. Use of any other tester can result in inaccurate
fi ndings. Battery on unit must be fully charged and properly connected before performing tests (a battery that
is hooked up or charged backward will crank engine but it won’t have spark). Be certain drive is in neutral and
all external loads are disconnected.
Test Ignition Systems
NOTE: If engine starts or runs during testing, you may need to ground kill lead to shut it down. Because you have
interrupted kill circuit, it may not stop using switch.
Isolate and verify trouble is within engine.
1. Locate connectors where wiring harnesses from engine and equipment are joined. Separate connectors and
remove white kill lead from engine connector. Rejoin connectors and position or insulate kill lead terminal so it
cannot touch ground. Try to start engine to verify whether reported problem is still present.
Condition Possible Cause Conclusion
Problem goes away. Electrical System Check key switch, wires, connections,
safety interlocks, etc.
Problem persists. Ignition or Electrical System Leave kill lead isolated until all testing
is completed.
Identify white kill lead of engine
wiring harness connector. Establish
a connection to a known good
ground location. Engine should kill
completely. If not or only one cylinder
is aff ected, test ignition modules and
white kill lead connection for aff ected
DSAI module (DSAI only).
4324 690 30 Rev. G KohlerEngines.com
Electrical System
Test for Spark
NOTE: If 2 testers are available, testing can be performed simultaneously for both cylinders. However, if only 1 tester
is available, 2 individual tests must be performed. Side not being tested must have spark plug lead connected
or grounded. Do not crank engine or perform tests with 1 spark plug lead disconnected and not grounded, or
permanent system damage may occur.
1. With engine stopped, disconnect 1 spark plug lead. Connect spark plug lead to post terminal of spark tester and
attach tester clip to a good engine ground.
2. Crank engine over, establishing a minimum of 550-600 RPM, and observe tester(s) for spark.
3. Repeat spark test on opposite cylinder if cylinders are being tested individually.
Condition Possible Cause Conclusion
Both cylinders have good spark but
engine runs poorly or existing plug
condition is questionable.
Spark Plug(s) Install new spark plug(s) and retest
engine performance.
If problem persists, check for timing
advance (DSAI and Smart-Spark
™
only).
1 cylinder has good spark and other
cylinder has no or intermittent spark.
Ignition Test ignition modules and
connections (DSAI and Smart-Spark
™
only).
Spark on both cylinders but power is
suspect.
Timing Advance Check for timing advance (DSAI and
Smart-Spark
™
only).
Test Timing Advance (DSAI and Smart-Spark
™
only)
1. Make a line near edge of fl ywheel screen with a marking pen, chalk, or narrow tape.
2. Connect an automotive timing light to cylinder that had good spark.
3. Run engine at idle and use timing light beam to locate line on screen. Draw a line on blower housing next to line
on screen. Accelerate to full throttle and watch for movement of line on screen relative to line on blower housing.
If both cylinders had good spark, repeat test on other cylinder.
Condition Possible Cause Conclusion
Line on screen did not move away
from line on blower housing during
acceleration.
Ignition Test ignition modules and
connections.
Lines made on blower housing not
90° apart.
Test Ignition Modules and Connections (DSAI only)
1. Remove blower housing from engine. Inspect wiring for any damage, cuts, bad crimps, loose terminals, or broken
wires. Check that connections are oriented properly on terminals of modules.
2. Disconnect leads from ignition module(s) and clean all of terminals (male and female) with aerosol electrical
contact cleaner to remove any old dielectric compound, dark residue, dirt, or contamination. Disconnect spark
plug leads from spark plugs.
3. Using a multi-meter, check that a proper ground is established between ground (black) lead of DSAI module
(closest to spark plug lead) and a known good ground location on engine.
4. Turn key switch to ON position and check for 12 volts at center/power (red) lead terminal of DSAI module. Use
same ground location for multi-meter as in checking for timing advance.
Condition Possible Cause Conclusion
All tests are OK but module has no
spark or fails to advance.
Ignition Module Replace aff ected module.
Any test is BAD. Ignition Module or Connections Determine cause and fi x as required;
retest.
Electrical System
44 24 690 30 Rev. GKohlerEngines.com
Test Ignition Modules and Connections (Smart-
Spark
™
only)
NOTE: Resistance values apply only to modules that
have been on a running engine. New service
modules may have higher resistance until they
have been run.
1. Remove blower housing from engine. Inspect wiring
for any damage, cuts, bad crimps, loose terminals,
or broken wires.
2. Disconnect leads from ignition module(s) and clean
all of terminals (male and female) with aerosol
electrical contact cleaner to remove any old
dielectric compound, dark residue, dirt, or
contamination. Disconnect spark plug leads from
spark plugs.
3. Remove one mounting screw from each ignition
module. If mounting screws are black, remove them
both and discard. Look in mounting hole with a
fl ashlight and use a small round wire brush to
remove any loose rust from laminations inside
mounting hole.
4. Use a digital ohmmeter to check resistance values
and compare them to ignition module resistance
table. When testing resistance to laminations, touch
probe to laminations inside screw hole, as some
laminations have a rust preventative coating on
surface which could alter resistance reading.
2
1
4
2
1
3
24 584 03
or
24 584 11
(1 11/16 in. High)
24 584 15-S
or
24 584 36-S
(2 1/16 in. High)
Test
(Use Digital
Ohmmeter)
From No.
1 to 4
From No.
2 to 4
From No.
3 to 4
24 584 03
24 584 11
(1 11/16 in. H)
945 to
1175 ohms
149 to
166 ohms
3750 to
7000 ohms
24 584 15-S
(2 1/16 in. H)
890 to
1175 ohms
119 to
136 ohms
5600 to
9000 ohms
24 584 36-S
(2 1/16 in. H)
590 to
616 ohms
183 to
208 ohms
8000 to
40,000 ohms
Ignition Module Resistance Table
Condition Possible Cause Conclusion
All resistance values are within
ranges specifi ed in table.
Ignition Module Gap Check and adjust ignition module
gap.
At least 1 resistance value is not
within ranges specifi ed in table.
Ignition Module Ignition module is faulty and should
be replaced.
5. Check and/or adjust ignition module air gap(s). An air gap of 0.28/0.33 mm (0.011/0.013 in.) must be maintained
under all three legs of ignition module(s). Checking/adjusting should be performed with parts at room temperature.
Condition Possible Cause Conclusion
Module was not loosened or
replaced.
Ignition Module Air Gap Check that specifi ed air gap is
present under all three legs. If gap is
correct, reinstall second mounting
screw removed earlier and recheck
gap after tightening.
Module was loosened or replaced. Ignition Module Adjust ignition module air gap.
a. Adjust ignition module air gap.
1. Turn fl ywheel magnet away from module position.
2. Attach module to mounting legs, pull it away from fl ywheel, and tighten screws to hold it temporarily.
3. Rotate fl ywheel so magnet is centered under module.
4. Position a 0.30 mm (0.012 in.) feeler gauge between magnet and all three legs of module. Ignition module
air gap is critical to proper system performance. Do not attempt to set it with a business card or folded
microfi che card. Use feeler gauge specifi ed.
5. Loosen mounting screws, allow magnet to pull module down against feeler gauge, and retighten mounting
screws.
6. Rotate fl ywheel to remove feeler gauge, position magnet back under module, and recheck that specifi ed
gap, minimum of 0.28 mm (0.011 in.), exists under each leg of module. When you are certain gap is correct,
torque module mounting screws to 4.0 N·m (35 in. lb.). Repeat these 6 steps to set other ignition module.
6. Reattach lead wires to ignition module(s), noting if resistance is felt, indicating a snug fi t between male and female
terminals. If any connections do not feel snug, disconnect lead, lightly pinch female terminal with a pliers, and
recheck fi t.
7. When integrity of all connections has been verifi ed, retest for spark.
4524 690 30 Rev. G KohlerEngines.com
Electrical System
Condition Possible Cause Conclusion
Strong, steady spark is now present
on both sides.
SAM Problem should be corrected. Go to
Test SAM step 4.
Still a spark problem. SAM Test SAM.
Test SAM
1. Trace red power source lead from SAM to harness connection. Separate connector and connect red lead of a DC
voltmeter to harness terminal. Trace ground lead from SAM (black on singles, green on twins) to grounding screw.
Connect black voltmeter lead to eyelet terminal of ground lead or ground screw/bolt. Check voltage with key
switch in both START and RUN positions. A minimum of 7.25 volts must be present.
a. If correct voltage is not measured, connect black voltmeter lead directly to negative (–) post of battery and test
voltage again in both key positions. If correct voltage is now indicated, check ground circuit connections. If
ground screw/bolt or any other fasteners in ground circuit are black (oxide-coated), replace them with zinc
plated (silver colored) fasteners.
b. If correct voltage is still not indicated, check harness connector terminal for a good connection and crimp to
lead. Then trace power source circuit back through harness, key switch, etc., looking for any poor connections,
or faulty circuits.
Condition Possible Cause Conclusion
Incorrect voltage is measured. Voltage Connect black voltmeter lead directly
to negative (–) post of battery and test
voltage again in both key positions.
If correct voltage is still not indicated,
check harness connector terminal for
a good connection and crimp to lead.
Then trace power source circuit back
through harness, key switch, etc.,
looking for any poor connections, or
faulty circuits.
Correct voltage is measured. Voltage Check ground circuit connections.
If ground screw/bolt or any other
fasteners in ground circuit are black
(oxide-coated), replace them with zinc
plated (silver colored) fasteners.
2. Disconnect all SAM leads, isolating it from engine. Test SAM according to style with tester 25 761 21-S (tests
ASAM style modules only), or tester 25 761 40-S (tests both ASAM and DSAM style modules). Use test
instructions following, or those provided with tester. If SAM tests bad, replace it.
3. Reattach SAM leads, verifying a snug fi t at ignition module terminals. If any connections do not feel snug,
disconnect lead, lightly pinch female terminal with a pliers, and recheck fi t.
4. Seal base of ignition module connections with GE/Novaguard G661 or equivalent dielectric compound. Beads
should overlap between two connections to form a solid bridge of compound. Do not put any compound inside
connectors.
24 584 15-S ignition modules have a separator/barrier between terminals. On these modules, seal base of
terminal if any portion of it is exposed, but it is not necessary to have overlapping beads of sealant between
connections.
5. Test for spark to be sure system is working, before you reinstall blower housing. If there is still a spark problem on
one side, replace that ignition module and recheck spark.
Test ASAM and DSAM
Allow 15-20 seconds for tester to clear and reset itself between tests or if test is interrupted before completion of test
cycle. Otherwise, a false reading may be displayed in form of a (–) or a faint 8.
Tester is powered by a 9-volt battery. Most SAMs are designed to operate down to a minimum of 7.25 volts. If tester
battery drops below that level, incorrect test readings will result. Tester battery should be checked periodically by
connecting a DC voltmeter between red and green lead wires, with tester connected to a SAM. Press and hold test
button for a full test cycle (F or P appears and then display shuts off ), while monitoring voltage reading on voltmeter.
If voltage drops below 7.5 at any time during cycle, 9-volt tester battery must be replaced. Use an extended life
(alkaline) battery.
To replace battery, remove outer set of screws on faceplate and carefully lift panel from body. Unplug connector and
pull battery (with mounting tape) off back of tester. Attach connector to new battery and mount battery to case with
double-backed tape. Reinstall faceplate and secure with four screws.
Electrical System
46 24 690 30 Rev. GKohlerEngines.com
To test ASAM only using 25 761 21-S tester:
NOTE: SAM must be at room temperature when tested.
Disconnect all SAM leads, isolating it from main
wiring harness and ignition module(s). Testing
may be performed with module mounted or
loose.
NOTE: Do not allow alligator clip leads to touch each
other.
1. Connect tester to SAM by attaching:
a. Yellow tester lead to long yellow module lead.
b. Brown tester lead to long brown module lead.
c. Red tester lead to red module lead.
d. Green tester lead to green module lead.
2. Check SAM part number stamped on side of
housing. Verify that you have an analog SAM
(ASAM) Part No. 24 584 10 or lower, not a digital
SAM (DSAM) Part No. 24 584 18 and higher. Follow
sub-step a for testing an ASAM with this tester.
Digital SAM (DSAM) modules require Tester 25 761
40-S for proper testing.
a. Depress tester button and hold it down. After
approximately four seconds, a numerical
sequence should be displayed, beginning with 1
or 2 and continuing to 8 or 9, followed by a letter
P (pass) or F (fail). Do not release tester button
until test cycle completes and display goes off . If
you get a (–) sign instead of numerical sequence,
and/or an F at end of cycle, SAM is probably bad.
Recheck all connections, check condition of
tester battery and repeat test. If you get (–) sign
and/or F again in retest, replace that SAM.
3. Disconnect yellow and brown tester leads from long
module leads. Connect brown tester lead to short
brown module lead. Connect yellow tester lead to
short yellow (or pink) module lead. Leave red and
green leads connected. Repeat step 2.
To test DSAM and ASAM using 25 761 40-S tester:
NOTE: Do not allow alligator clip leads to touch each
other.
NOTE: SAM must be at room temperature when tested.
Disconnect all SAM leads, isolating it from main
wiring harness and ignition module(s). Testing
may be performed with module mounted or
loose.
NOTE: Some modules contain two black ground leads,
with one containing a white stripe. Do not
connect to black/white lead with bullet connector
or a Fail test result will occur, regardless of
actual condition.
Test procedure for twin cylinder SAMs will vary slightly,
depending on whether module is analog (ASAM) or
digital (DSAM).
1. Check SAM part number stamped on end of
housing.
a. If it is an ASAM (24 584 09 or 24 584 10),
separate short yellow and brown leads from long
ones. Each set will be tested separately. Connect
tester to SAM as follows:
● Yellow tester lead to long yellow module lead.
● Brown tester lead to long brown module lead.
● Red tester lead to red module lead.
● Black tester lead to black or green module lead.
Remaining tester leads (pink and brown with black
band) are not used for testing ASAMs.
b. If it is a DSAM (all except 24 584 09 or 24 584
10), connect tester as follows:
● Yellow tester lead to long yellow module lead.
● Brown tester lead to long brown module lead.
● Red tester lead to red module lead.
● Black tester lead to green or black module ground
lead with eyelet terminal.
● Pink tester lead to short yellow or pink module
lead.
● Brown tester lead with black band or terminal to
short brown module lead.
2. Recheck SAM part number, noting last two digits.
Refer to table below or on tester faceplate to
determine test number to be used.
SAM Part
No.
12 584 12
24 584 09
24 584 10
24 584 30
24 584 31
24 584 33
24 584 34
24 584 32
Test No. 1234
SAM Part
No.
-
24 584 18
24 584 27
24 584 19
24 584 38
24 584 39
Test No. 5678
3. Depress tester button repeatedly until correct test
number appears on display. After a few seconds,
test number will fl ash three times and test will begin.
A reverse numerical sequence will be displayed,
starting with a 6 and progressing down to 1, followed
by a P (pass) or F (fail), indicating condition of part.
If testing an ASAM, return to step 1 and move yellow
and brown tester leads to short set of module leads,
then repeat test.
4. If you get a (–) sign instead of numerical sequence,
and/or an F at end of test cycle, recheck all of
connections, check condition of tester battery and
repeat test. If you get (–) or F sign again in retest
replace SAM.
BATTERY CHARGING SYSTEM
NOTE: Observe following guidelines to avoid damage to
electrical system and components:
● Make sure battery polarity is correct. A negative (–)
ground system is used.
● Disconnect rectifi er-regulator plug and/or wiring
harness plug before doing any electric welding on
equipment powered by engine. Disconnect all other
electrical accessories in common ground with engine.
● Prevent stator (AC) leads from touching or shorting
while engine is running. This could damage stator.
Most engines are equipped with a 15 or 20 amp
regulated charging system. Some have a 25 amp
regulated charging system. Some engines utilize a 3
amp unregulated system with optional 70 watt lighting
circuit.
4724 690 30 Rev. G KohlerEngines.com
Electrical System
15/20/25 Amp Regulated Charging System
Stator
Stator is mounted on crankcase behind fl ywheel. Follow procedures in Disassembly and Reassembly if stator
replacement is necessary.
Rectifi er-Regulator
NOTE: When installing rectifi er-regulator, take note of terminal markings and install plug(s) accordingly.
NOTE: Disconnect all electrical connections attached to rectifi er-regulator. Testing may be performed with rectifi er-
regulator mounted or loose. Repeat applicable test procedure 2 or 3 times to determine condition of part.
Rectifi er-regulator is mounted on blower housing. To replace it, disconnect plug(s), remove two mounting screws, and
ground wire or metal grounding strap.
Testing of rectifi er-regulator may be performed as follows, using appropriate Rectifi er-Regulator Tester.
To test 4/15 amp rectifi er-regulators:
1. Connect tester ground lead (with spring clamp) to
body of rectifi er-regulator being tested.
2. Connect tester red lead to B+ terminal of rectifi er-
regulator and 2 black tester leads to 2 AC terminals.
3. Plug tester into proper AC outlet/power for tester
being used. Turn on power switch. POWER light
should be illuminated and 1 of 4 status lights may be
on as well. This does not represent condition of part.
4. 4 amp: Press TEST button until a click is heard and
then release. Momentarily either HIGH, LOW, or
SHORT light will fl ash.
15 amp: Press TEST button until a click is heard and
then release. Momentarily 1 of 4 status lights will
illuminate, indicating condition of part.
To test 20/25 amp rectifi er-regulators:
1. 20 amp: Connect single lead adapter in between B+
(center) terminal of rectifi er-regulator being tested
and squared single end of tandem adapter lead.
25 amp: Connect squared single end of tandem lead
adapter to B+ (center/red) lead of rectifi er-regulator
being tested.
2. Connect tester ground lead (with spring clamp) to
body of rectifi er-regulator.
3. Connect red lead and 1 of black leads to pair of
terminals on open end of tandem adapter lead
(connections are not location specifi c).
4. Connect remaining black lead from tester to 1 of
outer AC terminals on rectifi er-regulator.
5. Plug tester into proper AC outlet/power for tester
being used. Turn on power switch. POWER light
should be illuminated and 1 of 4 status lights may be
on as well. This does not represent condition of part.
6. Press TEST button until a click is heard and then
release. Momentarily 1 of 4 status lights will
illuminate indicating partial condition of part.
Condition Conclusion
4 amp 15 Amp 20 amp 25 amp
OK (green) or HIGH light comes on
and stays steady.
Part is good and may be used. Disconnect tester black lead attached
to 1 AC terminal and reconnect it to
other AC terminal. Repeat test. If OK
(green) light comes on again, part is
good and may be used.
NOTE: A fl ashing LOW light can
also occur as a result of an
inadequate ground lead
connection. Make certain
connection location is clean
and clamp is secure.
Other lights come on.
Rectifi er-regulator is faulty and should not be used.
Electrical System
48 24 690 30 Rev. GKohlerEngines.com
15/20/25 Amp Battery Charging Systems
NOTE: Always zero ohmmeter on each scale before testing to ensure accurate readings. Voltage tests should be
made with engine running at 3600 RPM with no load. Battery must be good and fully charged.
When problems occur in keeping battery charged or battery charges at high rate, charging system or battery might be
causing problems.
To test charging system for no charge to battery:
1. Insert an ammeter in B+ lead from rectifi er-regulator.
With engine running at 3600 RPM and B+ (at
terminal on rectifi er-regulator) to ground using a DC
voltmeter.
If voltage is 13.8 volts or more, place a minimum
load of 5 amps (turn on lights if 60 watts or more, or
place a 2.5 ohm, 100 watt resistor across battery
terminals) on battery to reduce voltage. Observe
ammeter.
Condition Conclusion
Charge rate increases
when load is applied.
Charging system is OK
and battery was fully
charged.
Charge rate does not
increase when load is
applied.
Test stator and rectifi er-
regulator (steps 2 and 3).
2. Remove connector from rectifi er-regulator. With
engine running at 3600 RPM, measure AC voltage
across stator leads using an AC voltmeter.
Condition Conclusion
Voltage is 28 volts or
more.
Stator is OK. Rectifi er-
regulator is faulty; replace.
Voltage is less than 28
volts.
Stator is faulty; replace.
Test stator further using an
ohmmeter (steps 3 and 4).
3. With engine stopped, measure resistance across
stator leads using an ohmmeter.
Condition Conclusion
Resistance is 0.1/0.2
ohms.
Stator is OK.
Resistance is 0 ohms. Stator is shorted; replace.
Resistance is infi nity
ohms.
Stator is open; replace.
4. With engine stopped, measure resistance from each
stator lead to ground using an ohmmeter.
Condition Conclusion
Resistance is infi nity ohms
(no continuity).
Stator is OK (not shorted
to ground).
Resistance (or continuity)
measured.
Stator leads are shorted to
ground; replace.
To test charging system for battery continuously charging
at high rate:
1. With engine running at 3600 RPM, measure voltage
from B+ lead to ground using a DC voltmeter.
Condition Conclusion
Voltage is 14.7 volts or
less.
Charging system is OK.
Battery is unable to hold
charge; service or replace.
Voltage is more than 14.7
volts.
Faulty rectifi er-regulator;
replace.
4924 690 30 Rev. G KohlerEngines.com
Electrical System
3 Amp/70 Watt Lighting Stator
NOTE: Always zero ohmmeter on each scale before testing to ensure accurate readings. Voltage tests should be
made with engine running at 3600 RPM with no load. Battery must be good and fully charged.
To test charging system for no charge to battery:
1. With engine running in fast setting, measure voltage
across battery terminals using a DC voltmeter.
Condition Conclusion
Voltage is more than 12.5
volts.
Charging system is OK.
Voltage is 12.5 volts or
less.
Stator or diode are
probably faulty. Continue
testing stator and diode.
2. Remove connector from rectifi er-regulator. With
engine running in fast position, measure AC voltage
across stator leads using an AC voltmeter.
Condition Conclusion
Voltage is 28 volts or
more.
Stator winding is OK.
Voltage is less than 28
volts.
Test stator using an
ohmmeter.
3. With charging lead disconnected from battery and
engine stopped, measure resistance from charging
lead to ground using an ohmmeter. Note reading.
Reverse leads and measure resistance again.
In one direction, resistance should be infi nity ohms
(open circuit). With leads reversed, some resistance
should be measured (about midscale on Rx1 range).
Condition Conclusion
Resistance is low in both
directions.
Diode is shorted. Replace
diode.
Resistance is high in both
directions.
Diode or stator winding is
open. Continue testing.
4. Cut sleeving on charging lead to expose diode
connections.
Measure resistance from stator side of diode to
ground using an ohmmeter.
Condition Conclusion
Resistance is
approximately 1.07 ohms.
Stator winding is OK,
diode is open. Replace
diode.
Resistance is 0 ohms. Stator winding is shorted.
Replace stator.
Resistance is infi nity
ohms.
Stator winding or lead is
open. Replace stator.
To test charging system for no lights:
1. Make sure lights are not burned out.
Condition Conclusion
Burned out lights. Replace.
2. Disconnect lighting lead from wiring harness.
With engine running in fast setting, measure voltage
from lighting lead to ground using an AC voltmeter.
Condition Conclusion
Voltage is 15 volts or
more.
Stator is OK. Check for
loose connections or
shorts in wiring harness.
Voltage is less than 15
volts.
Test stator using an
ohmmeter.
3. With engine stopped, measure resistance of stator
from lighting lead to ground using an ohmmeter.
Condition Conclusion
Resistance is
approximately 0.4 ohms.
Stator is OK.
Resistance is 0 ohms. Stator is shorted. Replace
stator.
Resistance is infi nity
ohms.
Stator or lighting lead is
open. Replace stator.
Starter System
50
24 690 30 Rev. G
KohlerEngines.com
NOTE: Do not crank engine continuously for more than 10 seconds. Allow a 60 second cool down period between
starting attempts. Failure to follow these guidelines can burn out starter motor.
NOTE: If engine develops suffi cient speed to disengage starter but does not keep running (a false start), engine
rotation must be allowed to come to a complete stop before attempting to restart engine. If starter is engaged
while fl ywheel is rotating, starter pinion and fl ywheel ring gear may clash and damage starter.
NOTE: If starter does not crank engine, shut off starter immediately. Do not make further attempts to start engine until
condition is corrected.
NOTE: Do not drop starter or strike starter frame. Doing so can damage starter.
Engines in this series use inertia drive or solenoid shift starters.
Troubleshooting-Starting Diffi culties
Condition Possible Cause Conclusion
Starter does not energize. Battery Check specifi c gravity of battery. If low, recharge or replace
battery as necessary.
Wiring Clean corroded connections and tighten loose connections.
Replace wires in poor condition and with frayed or broken
insulation.
Starter Switch
or Solenoid
By-pass switch or solenoid with a jumper wire. If starter cranks
normally, replace faulty components. Remove and perform
individual solenoid test procedure.
Starter energizes but turns
slowly.
Battery Check specifi c gravity of battery. If low, recharge or replace
battery as necessary.
Brushes Check for excessively dirty or worn brushes and commutator.
Clean using a coarse cloth (not emery cloth).
Replace brushes if excessively or unevenly worn.
Transmission
or
Engine
Make sure clutch or transmission is disengaged or placed
in neutral. This is especially important on equipment with
hydrostatic drive. Transmission must be exactly in neutral to
prevent resistance which could keep engine from starting.
Check for seized engine components such as bearings,
connecting rod, and piston.
Starter System
24 690 30 Rev. G
KohlerEngines.com 51
INERTIA DRIVE ELECTRIC STARTERS
Inertia Drive Starter Components
Style A
Style B
Style A
Style B
A
G
H
D
F
I
B
C
E
A Dust Cover B Stop Nut
C Stop Gear Spacer D Anti-Drift Spring
E Dust Cover Spacer F Drive Pinion
G Retaining Ring H Spring Retainer
I Drive Nut (Collar)
When power is applied to starter, armature rotates. As
armature rotates, drive pinion moves out on drive shaft
splines and into mesh with fl ywheel ring gear. When
pinion reaches end of drive shaft, it rotates fl ywheel and
cranks engine.
When engine starts, fl ywheel rotates faster than starter
armature and drive pinion. This moves drive pinion out
of mesh with ring gear and into retracted position. When
power is removed from starter, armature stops rotating
and drive pinion is held in retracted position by anti-drift
spring.
Starter Drive Service
Style A
NOTE: Do not over-tighten vise as this can distort drive
pinion.
1. Remove starter from engine and remove dust cover.
2. Hold drive pinion in a vice with soft jaws when
removing or installing stop nut. Armature will rotate
with nut until drive pinion stops against internal
spacers.
3. Remove stop nut, stop gear spacer, anti-drift spring,
dust cover spacer, and drive pinion.
4. Clean splines on drive shaft thoroughly with solvent.
Dry splines thoroughly.
5. Apply a small amount of Kohler electric starter drive
lubricant, to splines. Use of other lubricants may
cause drive pinion to stick or bind.
6. Apply a small amount of Loctite
®
271
™
to stop nut
threads.
7. Install drive pinion, dust cover spacer, anti-drift
spring, stop gear spacer, and stop nut. Torque stop
nut to 17.0-19.2 N·m (150-170 in. lb.). Reinstall dust
cover.
Style B
1. Rubber dust cover has a molded lip on inside that
snaps into a groove in dust cover spacer Turn drive
pinion clockwise until it reaches fully extended
position. While holding it in extended position, grasp
tip of dust cover with a pliers or vise grip and pull it
free from spacer.
2. Disassemble snap ring removal tool.
3. Grasp spring retainer and push it toward starter,
compressing anti-drift spring and exposing retaining
ring.
4. Holding spring retainer in retracted position,
assemble inner halves of removal tool around
armature shaft with retaining ring in inner groove.
Slide collar over inner halves to hold them in
position.
5. Thread center screw into removal tool until you feel
resistance. Use a wrench (1-1/8 or adjustable) to
hold base of removal tool. Use another wrench or
socket (1/2 in. or 13 mm) to turn center screw
clockwise. Resistance against center screw will tell
you when retaining ring has popped out of groove in
armature shaft.
6. Remove drive components from armature shaft,
paying attention to sequence. If splines are dirty,
clean them with solvent.
7. Splines should have a light fi lm of lubricant.
Relubricate as necessary with Kohler starter drive
lubricant. Reinstall or replace drive components,
assembling them in reverse order they were
removed.
Starter System
52
24 690 30 Rev. G
KohlerEngines.com
Retaining Ring Installation
1. Position retaining ring in groove in one of inner
halves. Assemble other half over top and slide on
outer collar.
2. Be certain drive components are installed in correct
sequence onto armature shaft.
3. Slip tool over end of armature shaft, so retaining ring
inside is resting on end of shaft. Hold tool with one
hand, exerting slight pressure toward starter. Tap top
of tool with a hammer until you feel retaining ring
snap into groove. Disassemble and remove tool.
4. Squeeze retaining ring with a pliers to compress it
into groove.
5. Assemble inner halves with larger cavity around
spring retainer. Slide collar over them and thread
center screw in until resistance is felt.
6. Hold base of tool with a 1-1/8 wrench and turn
center screw clockwise with a 1/2 or 13 mm wrench
to draw spring retainer up around retaining ring. Stop
turning when resistance increases. Disassemble and
remove tool.
7. Reinstall dust cover.
Starter Disassembly
1. Remove drive components following instructions for
servicing drive.
2. Locate small raised line on edge of drive end cap.
On starters with style A commutator end caps, it will
be aligned with a pre-marked line on starter frame.
Frame is not pre-marked on starters with style B end
caps. Place a piece of masking tape on frame and
mark a line on tape in line with raised line on end
cap.
3. Remove thru bolts.
4. Remove commutator end cap with brushes and
brush springs (style A). Style B end caps remove as
a separate piece with brushes and carrier remaining
in frame.
5. Remove drive end cap.
6. Remove armature and thrust washer (if equipped)
from inside starter frame.
7. Remove brush/carrier assembly from frame (style B
starters).
Brush Replacement
Style A
NOTE: Use a brush holder tool to keep brushes in
pockets. A brush holder tool can easily be made
from thin sheet metal.
1. Remove brush springs from pockets in brush holder.
2. Remove self-tapping screws, negative (–) brushes,
and plastic brush holder.
3. Remove nut and fi ber washer from stud terminal.
Remove stud terminal with positive (+) brushes and
plastic insulating bushing from end cap.
4. Install insulating bushing on stud terminal of new
positive (+) brushes. Install stud terminal into
commutator end cap. Secure stud with fi ber washer
and screw.
5. Install brush holder, new negative (–) brushes, and
self-tapping screws.
6. Install brush springs and brushes into pockets in
brush holder. Make sure chamfered sides of brushes
are away from brush springs.
Style B
Starters with style B end caps have brushes in a plastic
carrier housing, separate from end cap. Replacement
brushes come preassembled in carrier housing, retained
with two carton staples.
Commutator Service
Clean commutator with a coarse, lint free cloth. Do not
use emery cloth.
If commutator is badly worn or grooved, turn it down on
a lathe or replace starter.
Starter Reassembly
1. Place thrust washer (if equipped) over drive shaft of
armature.
2. Insert armature into starter frame. Make sure
magnets are closer to drive shaft end of armature.
Magnets will hold armature inside frame.
3. Install drive end cap over drive shaft. Make sure
match marks on end cap and starter frame are
aligned.
4. Style A commutator end caps:
Install brush holder tool to keep brushes in pockets
of commutator end cap.
Align match marks on commutator end cap and
starter frame. Hold drive end and commutator end
caps fi rmly to starter frame. Remove brush holder
tool.
Style B commutator end caps:
If brush assembly is not being replaced, position
brushes in their pockets in carrier. Move them to
retracted position, and install carton staples to retain
them.
Align terminal stud block with notch in starter frame
and slide brush/carrier assembly into frame.
Commutator will push carton staples out as brush
assembly is installed. Position end cap over brush
assembly, so holes for thru bolts are aligned with
those in brush carrier.
5. Install thru bolts and tighten securely.
6. Lubricate drive shaft with Kohler starter drive
lubricant. Install drive components following
instructions for servicing starter drive.
Starter System
24 690 30 Rev. G
KohlerEngines.com 53
SOLENOID SHIFT ELECTRIC STARTERS
Solenoid Shift Starter Components
A
B
U
T
S
R
Q
P
O
N
M
L
K
J
I
H
G
F
E
D
C
A Tube B Washer
C Armature D Drive
E Stop F Retaining Ring
G Collar H Drive End Cap
I Screw J Plunger
K Spring L Lever
M Plate N Plug
O Solenoid P Frame and Field
Q Brush Holder R Nut
S
Commutator End
Plate
T Screw
U Bolt
When power is applied to starter electric solenoid moves
drive pinion out onto drive shaft and into mesh with
fl ywheel ring gear. When pinion reaches end of drive
shaft it rotates fl ywheel and cranks engine.
When engine starts and start switch is released, starter
solenoid is deactivated, drive lever moves back, and
drive pinion moves out of mesh with ring gear into
retracted position.
Nippondenso Starters
Starter Disassembly
NOTE: When removing lever and armature be careful
not to lose thrust washer.
1. Disconnect lead wire from solenoid.
2. Remove nuts securing solenoid, and remove
solenoid from starter assembly.
3. Remove thru bolts.
4. Remove commutator end cap.
5. Remove insulator and brush springs from brush
spring holder.
6. Remove armature from frame.
7. Remove drive lever and armature from drive end
cap.
8. Stop collar consists of two similar pieces held in
place by being snapped over a retainer. Retainer is
held in place by a groove in armature shaft. To
remove stop collar two pieces must be pried off
retainer.
9. When stop collars are removed retainer can be
removed from armature shaft. Do not reuse retainer.
Brush Replacement
Brushes in starter are part of starter frame. Brush kit
contains four replacement brushes and springs. If
replacement is necessary, all four brushes should be
replaced.
1. Remove brushes from brush holder, and remove
brush holder from frame.
2. Cut brush lead wire at edge of post with a pair of
nippers.
3. File off any burrs on post.
4. Replacement brushes have a solid portion which
should be crimped on post.
5. Solder crimped portion to post.
6. Replace brush holder in frame and place brushes in
brush holder. Reinstall springs.
Starter Reassembly
NOTE: Always use a new retainer. Tighten retainer in
groove to secure.
1. Insert rear stop collar on armature shaft.
2. Place retainer in groove on armature shaft.
3. Fit front stop collar over shaft and bring front and
rear stop collars together over retainer. Using two
pairs of pliers apply even force to two collars until
they snap over retainer and nest into one another.
4. Reassemble remaining components of starter in
reverse order from disassembly.
Delco-Remy Starters
Starter Disassembly
NOTE: Do not reuse old retainer.
NOTE: Do not soak armature or use solvent when
cleaning. Wipe clean using a soft cloth, or use
compressed air.
1. Remove hex nut and disconnect positive (+) brush
lead/bracket from solenoid terminal.
Starter System
54
24 690 30 Rev. G
KohlerEngines.com
2. Remove head screws securing solenoid to starter.
3. If solenoid was mounted with Phillips head screws,
separate solenoid and plunger spring from drive end
cap. If solenoid was mounted with external Torx
head screws, plunger is part of solenoid, unhook
plunger pin from drive lever. Remove gasket from
recess in housing.
4. Remove thru (larger) bolts.
5. Remove commutator end plate assembly, containing
brush holder, brushes, springs, and locking caps.
Remove thrust washer from inside commutator end.
6. Remove frame from armature and drive end cap.
7. Remove drive lever pivot bushing and backing plate
from end cap.
8. Take out drive lever and pull armature out of drive
end cap.
9. Remove thrust washer from armature shaft.
10. Push stop collar down to expose retaining ring.
11. Remove retainer from armature shaft. Save stop
collar.
12. Remove drive pinion assembly from armature.
13. Clean parts as required.
Inspection
Drive Pinion
Check and inspect following areas:
● Pinion teeth for abnormal wear or damage.
● Surface between pinion and clutch mechanism for
nicks or irregularities which could cause seal damage.
● Check drive clutch by holding clutch housing and
rotating pinion. Pinion should rotate in only 1 direction.
Brushes and Springs
Detail
A
A Wear Limit Length
Inspect both springs and brushes for wear, fatigue, or
damage. Measure length of each brush. Minimum length
for each brush is 7.6 mm (0.300 in.). Replace brushes if
they are worn, undersize, or condition is questionable.
Armature
Components and Details
A
B
A Commutator O.D. B Mica Insulation
D
E
C
C Insulation Check D Armature Coil
E Continuity Check
1. Clean and inspect commutator (outer surface). Mica
insulation must be lower than commutator bars
(undercut) to ensure proper operation of
commutator.
2. Use an ohmmeter set to Rx1 scale. Touch probes
between 2 diff erent segments of commutator, and
check for continuity. Test all segments. Continuity
must exist between all or armature is bad.
3. Check for continuity between armature coil
segments and commutator segments. There should
be no continuity. If continuity exists between any 2
armature is bad.
4. Check armature windings/insulation for shorting.
Shift Fork
Check that shift fork is complete, and pivot and contact
areas are not excessively worn, cracked, or broken.
Brush Replacement
4 brushes and springs are serviced as a set. Use a new
Kohler brush and spring kit if replacement is necessary.
1. Perform steps 1-5 in Starter Disassembly.
2. Remove screws securing brush holder assembly to
end cap (plate). Note orientation for reassembly
later. Discard old brush holder assembly.
3. Clean component parts as required.
4. New brushes and springs come preassembled in a
brush holder with a protective sleeve that will also
serve as an installation tool.
5. Perform Steps 10-13 in Starter Reassembly
sequence. Installation must be done after armature,
drive lever, and frame are installed, if starter has
been disassembled.
Starter System
24 690 30 Rev. G
KohlerEngines.com 55
Starter Reassembly
NOTE: Always use a new retainer. Do not reuse old
retainers that have been removed.
NOTE: Correctly installed, center pivot section of drive
lever will be fl ush or below machined surface of
housing.
1. Apply drive lubricant to armature shaft splines. Install
drive pinion onto armature shaft.
2. Install and assemble stop collar/retainer assembly.
a. Install stop collar down onto armature shaft with
counter bore (recess) up.
b. Install a new retainer in larger (rear) groove of
armature shaft. Squeeze with a pliers to
compress it in groove.
c. Slide stop collar up and lock it into place, so
recess surrounds retainer in groove. If necessary,
rotate pinion outward on armature splines against
retainer to help seat collar around retainer.
3. Install off set thrust (stop) washer so smaller off set of
washer faces retainer/collar.
4. Apply a small amount of oil to bearing in drive end
cap, and install armature with drive pinion.
5. Lubricate fork end and center pivot of drive lever
with drive lubricant. Position fork end into space
between captured washer and rear of pinion.
6. Slide armature into drive end cap and at same time
seat drive lever into housing.
7. Install backup washer, followed by rubber grommet,
into matching recess of drive end cap. Molded
recesses in grommet should be out, matching and
aligned with those in end cap.
8. Install frame, with small notch forward, onto
armature and drive end cap. Align notch with
corresponding section in rubber grommet. Install
drain tube in rear cutout, if it was removed
previously.
9. Install fl at thrust washer onto commutator end of
armature shaft.
10. Starter reassembly when replacing brushes/brush
holder assembly:
a. Hold starter assembly vertically on end housing,
and carefully position assembled brush holder
assembly, with supplied protective tube, against
end of commutator/armature. Mounting screw
holes in metal clips must be up/out. Slide brush
holder assembly down into place around
commutator, and install positive (+) brush lead
grommet in cutout of frame. Protective tube may
be saved and used for future servicing.
Starter reassembly when not replacing brushes/
brush holder assembly:
a. Carefully unhook retaining caps from brush
assemblies. Do not lose springs.
b. Position brushes back in their slots so they are
fl ush with I.D. of brush holder assembly. Insert
brush installation tool (with extension), or use
tube described above from a prior brush
installation, through brush holder assembly, so
holes in metal mounting clips are up/out.
c. Install brush springs and snap on retainer caps.
d. Hold starter assembly vertically on end housing,
and carefully place tool (with extension) and
assembled original brush holder assembly onto
end of armature shaft. Slide brush holder
assembly down into place around commutator,
install positive (+) brush lead grommet in cutout
of frame.
11. Install end cap onto armature and frame, aligning
thin raised rib in end cap with corresponding slot in
grommet of positive (+) brush lead.
12. Install thru bolts and brush holder mounting screws.
Torque bolts to 5.6-9.0 N·m (49-79 in. lb.) and brush
holder mounting screws to 2.5-3.3 N·m
(22-29 in. lb.).
13. Hook plunger behind upper end of drive lever and
install spring into solenoid. Insert mounting screws
through holes in drive end cap. Use these to hold
solenoid gasket in position, then mount solenoid.
Torque screws to 4.0-6.0 N·m (35-53 in. lb.).
14. Connect positive (+) brush lead/bracket to solenoid
and secure with nut. Torque nut to 8-11 N·m
(71-97 in. lb.). Do not overtighten.
Starter System
56
24 690 30 Rev. G
KohlerEngines.com
Solenoid Tests
NOTE: DO NOT leave 12 volt test leads connected to solenoid for any time over what is necessary for performing
each of individual tests. Internal damage to solenoid may occur.
Disconnect all leads from solenoid including positive brush lead attached to lower stud terminal. Remove mounting
hardware and separate solenoid from starter for testing.
To test solenoid pull-in coil/plunger:
Actuation
1. Use a 12 volt power supply and 2 test leads.
2. Connect 1 lead to fl at spade S/start terminal on
solenoid. Momentarily connect other lead to lower
large post terminal.
When connection is made solenoid should energize
(audible click) and plunger retract. Repeat test
several times.
Continuity
1. Use an ohmmeter set to audible or Rx2K scale, and
connect 2 ohmmeter leads to 2 large post terminals.
2. Perform solenoid pull-in coil/plunger actuation test
and check for continuity. Ohmmeter should indicate
continuity. Repeat test several times.
To test solenoid hold-in coil:
Function
1. Connect a 12 volt test lead to fl at spade S/start
terminal on solenoid and other lead to body or
mounting surface of solenoid.
2. Manually push plunger IN and check if coil holds
plunger retracted. Do not allow test leads to remain
connected to solenoid for a prolonged period of time.
Continuity
1. Use an ohmmeter set to audible or Rx2K scale, and
connect 2 ohmmeter leads to 2 large post terminals.
2. Perform preceding solenoid hold-in coil function test
and check for continuity. Meter should indicate
continuity. Repeat test several times.
Condition Conclusion
Solenoid fails to activate. Replace solenoid.
No continuity is indicated.
Plunger fails to stay retracted.
57
Disassembly/Inspection and Service
24 690 30 Rev. G KohlerEngines.com
External Engine Components
G
X
V
W
D
A
C
F
E
B
H
L
I
K
J
N
M
O
H
U
E
T
R
S
S
R
Q
Q
P
A Vaporizer B Lock-off /Filter C Regulator D Carburetor
E Gasket F Intake Manifold G Plastic Intake Manifold H Outer Baffl e
I Inner Baffl e J Breather Reed K Breather Gasket L Breather Cover
M Breather Tube N Oil Sentry
™
O Filter P Air Cleaner
Q Oil Filter R Nipple S Oil Cooler T Electric Starter
U Lifting Bracket V Fixed Guard W Blower Housing X Debris Shield
WARNING
Before working on engine or equipment, disable engine as
follows: 1) Disconnect spark plug lead(s). 2) Disconnect
negative (–) battery cable from battery.
Before disconnecting negative (–) ground cable, make sure
all switches are OFF. If ON, a spark will occur at ground
cable terminal which could cause an explosion if hydrogen
gas or LPG/NG fuel vapors are present.
Accidental Starts can cause severe injury or
death.
Disconnect and ground spark plug lead(s)
before servicing.
58
Disassembly/Inspection and Service
KohlerEngines.com 24 690 30 Rev. G
Remove LPG/NG Components
WARNING
Explosive Fuel can cause fi res and severe
burns.
If a gaseous odor is detected, ventilate area
and contact an authorized service technician.
LPG is extremely fl ammable and is heavier than air
and tends to settle in low areas where a spark or fl ame
could ignite gas. Do not start or operate this engine
in a poorly ventilated area where leaking gas could
accumulate and endanger safety of persons in area.
NG is extremely fl ammable, is lighter than air, and
rises. Do not start or operate this engine in a poorly
ventilated area where leaking gas could accumulate
and endanger safety of persons in area.
To ensure personal safety, installation and repair of
LPG/NG fuel supply systems must be performed only
by qualifi ed LPG/NG system technicians. Improperly
installed and maintained LPG/NG equipment could
cause fuel supply system or other components to
malfunction, causing gas leaks.
Observe federal, state and local laws governing LPG/
NG fuel, storage, and systems.
1. Remove fuel lines and vacuum line from regulator.
Remove screws securing regulator and bracket.
2. For LPG engines, remove fuel lines from vaporizer
and lock-off /fi lter. Remove lock-off /fi lter from
vaporizer. Remove screws securing vaporizer and
bracket.
Remove Control Panel (if equipped)
1. Disconnect Oil Sentry
™
indicator light wires.
2. Disconnect choke control cable from control bracket.
3. Disconnect throttle control cable or shaft.
4. Remove panel from blower housing.
Clean all parts thoroughly as engine is disassembled.
Only clean parts can be accurately inspected
and gauged for wear or damage. There are many
commercially available cleaners that will quickly remove
grease, oil, and grime from engine parts. When such a
cleaner is used, follow manufacturer’s instructions and
safety precautions carefully.
Make sure all traces of cleaner are removed before
engine is reassembled and placed into operation. Even
small amounts of these cleaners can quickly break down
lubricating properties of engine oil.
Disconnect Spark Plug Leads
NOTE: Pull on boot only, to prevent damage to spark
plug lead.
1. Disconnect leads from spark plugs.
2. Shut off fuel supply.
Drain Oil from Crankcase and Remove Oil Filter
1. Remove oil fi ll cap, dipstick, and 1 oil drain plug.
2. Allow ample time for oil to drain from crankcase and
oil fi lter.
3. Remove and discard oil fi lter.
4. An oil cooler is standard equipment on some models
and an option on others. It may be a cast aluminum
housing, part of oil fi lter adapter, or attached to
blower housing, separated from oil fi lter adapter. If
equipped, remove adapter and cooler.
Remove Muffl er
Remove exhaust system and attaching hardware from
engine. On engines equipped with a port liner, remove it
now.
Remove Air Cleaner Assembly
1. Unhook latches or loosen knob and remove cover.
2. Remove wing nut from element cover.
3. Remove element cover, air cleaner element with
precleaner and stud seal.
4. Remove screws securing bracket and base.
Additional rear screws must be removed if engine
contains a rear air cleaner support bracket.
5. Remove bracket then remove base and gasket while
carefully pulling rubber breather tube through base.
6. Remove rubber breather tube from breather cover.
59
Disassembly/Inspection and Service
24 690 30 Rev. G KohlerEngines.com
Remove Carburetor (Mechanical Governor)
WARNING
Explosive Fuel can cause fi res and severe
burns.
If a gaseous odor is detected, ventilate area
and contact an authorized service technician.
LPG is extremely fl ammable and is heavier than air
and tends to settle in low areas where a spark or fl ame
could ignite gas. Do not start or operate this engine
in a poorly ventilated area where leaking gas could
accumulate and endanger safety of persons in area.
NG is extremely fl ammable, is lighter than air, and
rises. Do not start or operate this engine in a poorly
ventilated area where leaking gas could accumulate
and endanger safety of persons in area.
To ensure personal safety, installation and repair of
LPG/NG fuel supply systems must be performed only
by qualifi ed LPG/NG system technicians. Improperly
installed and maintained LPG/NG equipment could
cause fuel supply system or other components to
malfunction, causing gas leaks.
Observe federal, state and local laws governing LPG/
NG fuel, storage, and systems.
1. Disconnect ground lead, if equipped.
2. Remove carburetor mounting screws or nuts.
3. Remove carburetor, throttle linkage and governor
lever as an assembly.
4. Remove carburetor gasket.
5. If necessary, carburetor, throttle linkage and
governor lever can be separated. Reattach bushings
to linkage following separation to avoid losing them.
Remove Throttle and Choke Controls (Mechanical
Governor)
Control Bracket Components (Mechanical
Governor)
E
F
D
C
B
A
A Choke Linkage B Control Bracket
C Spring D Governor Lever
E Nut F Throttle Linkage
1. Remove screws securing control bracket and rear air
cleaner bracket (some models) to cylinder heads.
2. Mark spring hole locations and disconnect spring
from governor lever.
3. Remove choke linkage from choke actuator lever
and carburetor.
Remove External Governor Controls (Mechanical
Governor)
Loosen nut and remove governor lever from cross shaft.
Leave lever attached to throttle linkage and lay assembly
on top of crankcase.
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Disassembly/Inspection and Service
KohlerEngines.com 24 690 30 Rev. G
Remove Carburetor and Electronic Governor
Assembly
E
A
G
B
D
C
F
A Carburetor Fitting B Carburetor
C
Carburetor Throttle
Lever
D Bushing
E Throttle Linkage F
Electronic Governor
Assembly
G
Electronic Governor
Connector
1. Loosen hose clamp and remove fuel hose from
carburetor fi tting.
2. Remove screws securing carburetor to intake
manifold.
3. Disconnect bushing securing throttle linkage to
carburetor throttle lever. Lift carburetor off intake
manifold and discard carburetor gasket.
4. Disconnect electronic governor connector from
wiring harness.
5. Remove screws securing electronic governor
assembly to crankcase; remove electronic governor
assembly with throttle linkage.
Remove Oil Sentry
™
(if equipped)
1. Disconnect lead from Oil Sentry
™
switch.
2. Remove Oil Sentry
™
switch from breather cover.
Remove Electric Starter Motor
1. Disconnect leads from starter.
2. Remove screws.
3. Remove starter assembly and any spacers (if used).
Remove Outer Baffl es and Blower Housing
1. Disconnect plug from rectifi er-regulator on blower
housing.
2. Use tip of dipstick or a similar small fl at tool to bend
locking tang, then remove B+ (center lead) from
terminal plug. This will allow blower housing to be
removed without disturbing wiring harness.
3. Rectifi er-regulator does not have to be detached
from blower housing. If engine is equipped with
SMART-SPARK
™
SAM module should be removed
from cylinder baffl e or blower housing. Module will
hang loose as part of wiring harness.
4. Remove screws securing outer baffl es. Note location
of any lifting strap and position of two short screws
(one each side on bottom) for reassembly.
5. Remove outer baffl es on both sides.
6. On engines equipped with a metal debris screen,
remove screen before removing blower housing.
Plastic debris screens can be removed after blower
housing is removed.
7. Remove lower blower housing screw and washer
securing rectifi er-regulator ground lead or grounding
strap.
8. Remove remaining screws and detach blower
housing.
9. Disconnect plug from key switch in blower housing if
engine is equipped.
Remove Inner Baffl es and Breather Cover
Inner (valley) baffl es are attached at one corner using
same fasteners as breather cover.
1. Remove screws securing inner baffl es.
2. Remove both inner baffl es.
3. Remove two remaining screws holding breather
cover to crankcase.
4. Pry under protruding edge of breather cover with a
screwdriver to break RTV or gasket seal. Do not pry
on sealing surfaces as it could cause damage
resulting in leaks. Most engines use a formed gasket
rather than RTV sealant.
5. Remove breather cover and gasket (if used).
6. Remove breather fi lter from chamber.
7. Remove screw, breather reed retainer and breather
reed.
Remove Intake Manifold
1. Remove screws securing intake manifold to cylinder
heads. Note which screws hold wiring clamps.
2. Remove intake manifold and intake manifold gaskets
(aluminum intake manifolds) or O-rings (plastic
intake manifolds).
3. Leave wiring harness attached to manifold.
61
Disassembly/Inspection and Service
24 690 30 Rev. G KohlerEngines.com
Cylinder Head Components
B
C
D
E
G
K
F
H
I
J
L
M
N
O
P
A
A Valve B Stud C Gasket D Spark Plug
E Cap F Valve Stem Seal G Hydraulic Lifter H Retainer
I Valve Spring J Valve Spring Retainer K Push Rod L Valve Keeper
M Rocker Arm N Rocker Arm Pivot O Valve Cover O-ring P Valve Cover
Remove Valve Covers
Three valve cover designs have been used. Earliest
type used a gasket and RTV sealant between cover and
sealing surface of cylinder head. Second type had a
black O-ring installed in a groove on underside of cover
and may have metal spacers in bolt holes. Latest design
uses a brown O-ring, and bolt holes spacers are molded
in place.
1. Remove screws securing each valve cover. Note
position of any attached brackets or lifting straps.
2. Remove valve covers, valve cover gaskets or
O-rings and any brackets or lifting straps. Note
which side of engine has oil fi ll valve cover.
Remove Spark Plugs
Remove spark plug from each cylinder head.
Remove Cylinder Heads and Hydraulic Lifters
NOTE: Cylinder heads are retained using either screws
or nuts and washers on studs. Do not
interchange or mix components, as cylinder
heads may have diff erent machining, unique to
each fastening method.
NOTE: Exhaust lifters are located on output shaft side
of engine while intake lifters are located on fan
side of engine. Cylinder head number is
embossed on outside of each cylinder head.
1. Remove screws or nuts and washers securing each
cylinder head. Unless screws are damaged or
questionable, they can be reused. Discard nuts and
washers once removed; do not reuse. Studs (if
present) should only be removed if damaged or if
cylinder reconditioning is necessary. Once removed,
they must be replaced.
2. Mark position of push rods as either intake or
exhaust and cylinder 1 or 2. Push rods should
always be reinstalled in same positions.
3. Carefully remove push rods, cylinder heads and
head gaskets.
4. Remove lifters from lifter bores. Use a Hydraulic
Lifter Tool. Do not use a magnet to remove lifters.
Mark lifters by location, as either intake or exhaust
and cylinder 1 or 2. Hydraulic lifters should always
be reinstalled in same position.
62
Disassembly/Inspection and Service
KohlerEngines.com 24 690 30 Rev. G
Disassemble Cylinder Heads
NOTE: These engines use valve stem seals on intake valves. Use a new seal whenever valve is removed or if seal is
deteriorated in any way. Never reuse an old seal.
1. Remove screws, rocker arm pivots and rocker arms from cylinder head. Note screw color for reassembly.
2. Compress valve springs using a valve spring compressor.
3. Once valve spring is compressed, remove following items.
● Valve spring keepers.
● Valve spring retainers.
● Valve springs.
● Valve spring caps.
● Intake and exhaust valves (mark position).
● Valve stem seals (intake valve only).
4. Repeat above procedure for other cylinder head. Do not interchange parts from one cylinder head to other.
Inspection and Service
Valve Details
EXHAUST VALVE INTAKE VALVE
EXHAUST
INSERT
INTAKE
INSERT
H
H
G
G
E
E
F
F
A
A
C
D
D
B
B
Dimension Intake Exhaust
A Seat Angle 89° 89°
B Insert O.D. 36.987/37.013 mm (1.4562/1.4572 in.) 32.987/33.013 mm (1.2987/1.2997 in.)
C Guide Depth 4 mm (0.1575 in.) 6.5 mm (0.2559 in.)
D Guide I.D. 7.038/7.058 mm (0.2771/0.2779 in.) 7.038/7.058 mm (0.2771/0.2779 in.)
E Valve Head Diameter 33.37/33.63 mm (1.3138/1.3240 in.) 29.37/29.63 mm (1.1563/1.1665 in.)
F Valve Face Angle 45° 45°
G Valve Margin (Min.) 1.5 mm (0.0591 in.) 1.5 mm (0.0591 in.)
H Valve Stem Diameter 6.982/7.000 mm (0.2749/0.2756 in.) 6.970/6.988 mm (0.2744/0.2751 in.)
63
Disassembly/Inspection and Service
24 690 30 Rev. G KohlerEngines.com
After cleaning, check fl atness of cylinder head and
corresponding top surface of crankcase, using a surface
plate or precision straight edge and feeler gauge. For all
except 83 mm bore maximum allowable out of fl atness
is 0.076 mm (0.003 in.). For 83 mm bore maximum
allowable out of fl atness is 0.1 mm (0.004 in.).
Carefully inspect valve mechanism parts. Inspect valve
springs and related hardware for excessive wear or
distortion. Check valves and valve seat area or inserts
for evidence of deep pitting, cracks, or distortion. Check
clearance of valve stems in guides.
Hard starting or loss of power accompanied by high
fuel consumption may be symptoms of faulty valves.
Although these symptoms could also be attributed to
worn rings, remove and check valves fi rst. After removal,
clean valve heads, faces, and stems with a power wire
brush.
Then, carefully inspect each valve for defects such as a
warped head, excessive corrosion, or a worn stem end.
Replace valves found to be in bad condition.
Valve Guides
If a valve guide is worn beyond specifi cations, it will not
guide valve in a straight line. This may result in burnt
valve faces or seats, loss of compression, and excessive
oil consumption.
To check valve guide-to-valve stem clearance,
thoroughly clean valve guide and, using a split-ball
gauge, measure inside diameter of guide. Then, using
an outside micrometer, measure diameter of valve stem
at several points on stem where it moves in valve guide.
Use largest stem diameter to calculate clearance by
subtracting stem diameter from guide diameter. If intake
clearance exceeds 0.038/0.076 mm (0.0015/0.0030 in.)
or exhaust clearance exceeds 0.050/0.088 mm
(0.0020/0.0035 in.), determine whether valve stem or
guide is responsible for excessive clearance.
Maximum (I.D.) wear on intake valve guide is 7.134 mm
(0.2809 in.) while 7.159 mm (0.2819 in.) is maximum
allowed on exhaust guide. Guides are not removable but
can be reamed 0.25 mm (0.010 in.) oversize. Valves with
0.25 mm oversize stems must then be used.
If guides are within limits but valve stems are worn
beyond limits, install new valves.
Valve Seat Inserts
Hardened steel alloy intake and exhaust valve seat
inserts are press fi tted into cylinder head. Inserts are
not replaceable but can be reconditioned if not too badly
pitted or distorted. If cracked or badly warped, cylinder
head should be replaced.
Recondition valve seat inserts following instructions
provided with valve seat cutter being used. Final cut
should be made with an 89° cutter as specifi ed for
valve seat angle. Cutting proper 45° valve face angle
as specifi ed, and proper valve seat angle (44.5°, half of
full 89° angle), will achieve desired 0.5° (1.0° full cut)
interference angle where maximum pressure occurs on
outside diameters of valve face and seat.
Lapping Valves
NOTE: Exhaust valves that are black in color cannot be
ground and do not require lapping.
Reground or new valves must be lapped in, to provide
proper fi t. Use a hand valve grinder with a suction cup
for fi nal lapping. Lightly coat valve face with a fi ne grade
of grinding compound, then rotate valve on its seat with
grinder. Continue grinding until a smooth surface is
obtained on seat and on valve face. Thoroughly clean
cylinder head in soap and hot water to remove all traces
of grinding compound. After drying cylinder head, apply
a light coating of SAE 10 oil to prevent rusting.
Intake Valve Stem Seal
These engines use valve stem seals on intake valves.
Always use a new seal when valves are removed
from cylinder head. Seals should also be replaced if
deteriorated or damaged in any way. Never reuse an old
seal.
Hydraulic Lifters Inspection
Check base surface of hydraulic lifters for wear or
damage. If lifters need to be replaced, apply a liberal
coating of Kohler lubricant to base of each new lifter
before it is installed.
Bleeding Lifters
To prevent a possible bent push rod or broken rocker
arm, it is important to bleed any excess oil out of lifters
before they are installed.
1. Cut a 50-75 mm (2-3 in.) piece from end of an old
push rod and chuck it in a drill press.
2. Lay a rag or shop towel on table of drill press and
place lifter, open end up, on towel.
3. Lower chucked push rod until it contacts plunger in
lifter. Slowly pump plunger 2 or 3 times to force oil
out of feed hole in side of lifter.
64
Disassembly/Inspection and Service
KohlerEngines.com 24 690 30 Rev. G
Inspection
Inspect fl ywheel for cracks and fl ywheel keyway for
damage. Replace fl ywheel if it is cracked. Replace
fl ywheel, crankshaft, and key if fl ywheel key is sheared
or keyway is damaged.
Inspect ring gear for cracks or damage. Kohler does not
provide ring gear as a serviceable part. Replace fl ywheel
if ring gear is damaged.
Remove Stator and Backing Plates
1. Remove screws securing backing plates and stator
wire bracket (if equipped). Remove backing plates
and stator wire bracket.
2. Remove screws and stator.
Remove Ignition Modules
1. Disconnect lead(s) from each ignition module.
Modules for non-SMART-SPARK
™
ignition systems
have only one kill lead.
2. Rotate fl ywheel so magnet is away from modules.
3. Remove mounting screws and ignition modules.
Note position of ignition modules.
Remove Debris Screen and Fan
1. Small metal retainers are typically attached on 3 of 7
mounting posts for positive retention of plastic debris
screen. Use a hook-end tool next to post and pull
outward to separate small metal retainers. Then
unsnap fan from remaining mounting posts.
2. Remove screws and fan.
Remove Flywheel
NOTE: Always use a fl ywheel strap wrench or holding
tool to hold fl ywheel when loosening or
tightening fl ywheel screw. Do not use any type
of bar or wedge to hold fl ywheel. Use of such
tools could cause fl ywheel to become cracked or
damaged.
NOTE: Always use a fl ywheel puller to remove fl ywheel
from crankshaft. Do not strike crankshaft or
fl ywheel, as these parts could become cracked
or damaged. Striking puller or crankshaft can
cause crank gear to move, aff ecting crankshaft
end play.
1. Use a fl ywheel strap wrench or holding tool (see
Tools and Aids) to hold fl ywheel and loosen screw
securing fl ywheel to crankshaft.
2. Remove screw and washer.
3. Use a puller to remove fl ywheel from crankshaft.
4. Remove woodruff key from crankshaft.
Flywheel/Ignition Components
F
G
E
C
K
L
O
M
N
H
P
B
I
D
J
A
A Debris Screen B Fan C Flywheel Screw D Washer
E Flywheel F Magnet G Stator H Ignition Module
I Backing Plate J Woodruff Key K Spring Washer L Spacer
M Ring Support N Metal Debris Screen O Washer P
Metal Debris Screen
Assembly
65
Disassembly/Inspection and Service
24 690 30 Rev. G KohlerEngines.com
Crankcase Components
A
Q
P
H
F
E
B
A
C
D
G
I
L
J
O
N
M
R
K
Y
S
V
U
T
W
X
A Oil Seal B Closure Plate (Style A) C
Gerotor Gears
(Style A)
D Dipstick Tube
E
Oil Pick-Up Tube
(Style A)
F
Oil Pump Assembly
(Style A)
G Governor Gear Shaft H Governor Gear
I Camshaft J Piston Pin K Piston Ring Set L Piston Pin Retainer
M Piston N Connecting Rod O
Connecting Rod End
Cap
P Crankshaft
Q Oil Drain Plug R Governor Cross Shaft S Closure Plate (Style B) T
Outer Gerotor Gear
(Style B)
U Ball (Style B) V Spring (Style B) W
Oil Pump Cover O-ring
(Style B)
X
Oil Pump Assembly
(Style B)
Y
Oil Pick-Up Tube
(Style B)
Remove Closure Plate Assembly
1. Remove screws securing closure plate to crankcase.
2. Locate splitting tabs cast into perimeter of closure
plate. Insert drive end of a 1/2 in. breaker bar
between top splitting tab and crankcase. Hold
handle horizontal and pull toward you to break RTV
seal. If necessary, pry at bottom tabs also. Do not
pry on sealing surfaces as this could cause leaks.
Carefully pull closure plate from crankcase.
Inspection
Inspect oil seal in closure plate and remove it if it is worn
or damaged. Refer to Install Closure Plate Oil Seal in
Reassembly for new oil seal installation.
Inspect main bearing surface for wear or damage. Refer
to specifi cations. Replace closure plate assembly if
required.
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KohlerEngines.com 24 690 30 Rev. G
Governor Gear Assembly
Governor Shaft Component and Details
C
B
A
A Gear Shaft
B 19.40 mm (0.7638 in.)
C 34.0 mm (1.3386 in.) 33.5 mm (1.3189 in.)
Governor gear assembly is located inside closure plate.
If service is required, refer to Inspection, Disassembly,
and Reassembly procedures.
Inspection
Inspect governor gear teeth. Replace gear if it is worn,
chipped, or if any teeth are missing. Inspect governor
weights. They should move freely in governor gear.
Disassembly
NOTE: Governor gear is held onto shaft by small
molded tabs in gear. When gear is removed from
shaft, these tabs are destroyed and gear must
be replaced. Therefore, remove gear only if
absolutely necessary.
Governor gear must be replaced once it is removed from
closure plate.
1. Remove regulating pin and governor gear assembly.
2. Remove locking tab thrust washer located under
governor gear assembly.
3. Carefully inspect governor gear shaft and replace it
only if it is damaged. After removing damaged shaft,
press or lightly tap replacement shaft into closure
plate to depth shown.
Reassembly
1. Install locking tab thrust washer on governor gear
shaft with tab down.
2. Position regulating pin within governor gear/fl yweight
assembly and slide both onto governor shaft.
Oil Pump Assembly (Style A)
F
H
I
G
C
B
J
A
E
D
1
2
A
Oil Pump
(Original Style A)
B
Oil Pump
(Later Style A)
C Oil Pickup Tube D Roll Pin
E Piston F Spring G O-ring H Plastic Oil Pickup
I
One-Piece Relief
Valve
J
Torque Sequence
(Style A)
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24 690 30 Rev. G KohlerEngines.com
Oil Pump Assembly (Style A)
Oil pump is mounted inside closure plate. If service is
required, continue with Disassembly, Inspection, and
Reassembly.
Disassembly
1. Remove screws.
2. Remove oil pump assembly from closure plate.
3. Remove oil pump rotor.
4. Remove oil pickup by unhooking locking clip, and
pulling it free from oil pump body.
5. If relief valve is similar to shown, drive out pin to
remove oil pressure relief valve piston and spring.
Refer to following inspection and reassembly
procedures.
If relief valve is a one-piece style, staked to oil pump
housing removal should not be attempted, nor is
internal servicing possible. If a problem with relief
valve is encountered, oil pump should be replaced.
Inspection
Inspect oil pump housing, gear, and rotors for nicks,
burrs, wear, or any visible damage. If any parts are worn
or damaged, replace oil pump.
Inspect oil pressure relief valve piston. It should be free
of nicks or burrs.
Check spring for wear or distortion. Free length of spring
should be approximately 47.4 mm (1.8 in.). Replace
spring if it is distorted or worn.
Reassembly
1. Install pressure relief valve piston and spring.
2. Install oil pickup to oil pump body. Lubricate O-ring
with oil and make sure it remains in groove as
pickup is being installed.
3. Install rotor.
4. Install oil pump body to closure plate and secure
with screws. Torque screws as follows:
a. Install fastener into screw location 1 and lightly
tighten to position pump.
b. Install fastener into screw location 2 and fully
torque to recommended value.
c. Torque fastener in screw location 1 to
recommended value.
First Time Installation: 10.7 N·m (95 in. lb.)
All Reinstallations: 6.7 N·m (60 in. lb.)
5. After torquing, rotate gear and check for freedom of
movement. Make sure there is no binding. If binding
occurs, loosen screws, reposition pump, retorque
screws and recheck movement.
Oil Pump Assembly (Style B)
Oil pump is mounted inside closure plate. If service is
required, continue with Disassembly, Inspection, and
Reassembly.
Disassembly
1. Remove screws.
2. Lift oil pump assembly from closure plate. Remove
outer gerotor gear from closure plate.
3. Ensure ball and spring remain installed in pressure
relief hole of closure plate. If ball and spring fall out
of pressure relief hole, see reassembly for correct
installation.
4. Remove oil pump cover O-ring from groove in
closure plate.
Inspection
Inspect oil pump housing, gear, and rotors for nicks,
burrs, wear, or any visible damage. Inspect oil pump
cover O-ring for cuts, nicks, or any visible damage. If any
parts are worn or damaged, replace oil pump assembly
and/or O-ring. Check oil pickup screen for damage or
restriction, replace if necessary.
Reassembly
1. Lubricate outer gerotor gear with oil. Install outer
gerotor gear through shaft of oil pump, around inner
gerotor gear. Matching molding dots on inner and
outer gerotor gears is not necessary and will not
aff ect oil pump effi ciency.
2. Reinstall ball, then spring into pressure relief hole in
closure plate.
3. Reinstall O-ring into groove in closure plate; make
sure it is fully seated in groove.
4. Install oil pump inserting center shaft into
corresponding recess in closure plate. Apply
consistent downward pressure to oil pump cover,
compressing oil pressure relief spring and start
screws. Secure oil pump by torquing screws (in no
specifi c sequence) to 9.0 N·m (80 in. lb.).
5. After torquing, rotate gear and check for freedom of
movement. Make sure there is no binding. If binding
occurs, loosen screws, reposition pump, retorque
screws and recheck movement.
Remove Camshaft
Remove camshaft and shim.
Inspection and Service
NOTE: To prevent repeat failures, camshaft and
crankshaft should always be replaced as a set.
Check lobes of camshaft for wear or damage. See
Specifi cations for minimum lift tolerance. Inspect
cam gear for badly worn, chipped or missing teeth.
Replacement of camshaft will be necessary if any of
these conditions exist.
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Disassembly/Inspection and Service
KohlerEngines.com 24 690 30 Rev. G
Remove Connecting Rods with Pistons and Rings
NOTE: If a carbon ridge is present at top of either
cylinder bore, use a ridge reamer tool to remove
ridge before attempting to remove piston.
NOTE: Cylinders are numbered on crankcase. Use
numbers to mark each end cap, connecting rod
and piston for reassembly. Do not mix end caps
and connecting rods.
1. Remove screws securing closest connecting rod end
cap. Remove end cap.
2. Carefully remove connecting rod and piston
assembly from cylinder bore.
3. Repeat above procedures for other connecting rod
and piston assembly.
Piston and Rings
Piston and Rings Components and Details
A
B
C
D
E
A Piston B
Top Compression
Ring
C
Middle Compression
Ring
D Rails
E Expander F
Oil Control Ring
(3 Piece)
NOTE: Rings must be installed correctly. Ring
installation instructions are usually included with
new ring sets. Follow instructions carefully. Use
a piston ring expander to install rings. Install
bottom (oil control) ring fi rst and top
compression ring last.
Scuffi ng and scoring of pistons and cylinder walls occurs
when internal engine temperatures approach welding
point of piston. Temperatures high enough to do this are
created by friction, which is usually attributed to improper
lubrication and/or overheating of engine.
Normally, very little wear takes place in piston boss-
piston pin area. If original piston and connecting rod can
be reused after new rings are installed, original pin can
also be reused but new piston pin retainers are required.
Piston pin is included as part of piston assembly – if pin
boss in piston or pin are worn or damaged, a new piston
assembly is required.
Ring failure is usually indicated by excessive oil
consumption and blue exhaust smoke. When rings fail,
oil is allowed to enter combustion chamber where it is
burned along with fuel. High oil consumption can also
occur when piston ring end gap is incorrect because
ring cannot properly conform to cylinder wall under this
condition. Oil control is also lost when ring gaps are not
staggered during installation.
When cylinder temperatures get too high, lacquer and
varnish collect on pistons causing rings to stick, which
results in rapid wear. A worn ring usually takes on a
shiny or bright appearance.
Scratches on rings and pistons are caused by abrasive
material such as carbon, dirt, or pieces of hard metal.
Detonation damage occurs when a portion of fuel charge
ignites spontaneously from heat and pressure shortly
after ignition. This creates two fl ame fronts which meet
and explode to create extreme hammering pressures on
a specifi c area of piston. Detonation generally occurs
from using low octane fuels.
Preignition or ignition of fuel charge before timed spark
can cause damage similar to detonation. Preignition
damage is often more severe than detonation damage.
Preignition is caused by a hot spot in combustion
chamber from sources such as glowing carbon deposits,
blocked cooling fi ns, an improperly seated valve, or
wrong spark plug(s).
Replacement pistons are available in STD bore size, and
in 0.25 mm (0.010 in.), and 0.50 mm (0.020 in.) oversize.
Replacement pistons include new piston ring sets and
new piston pins.
Replacement ring sets are also available separately
for STD, 0.25 mm (0.010 in.), and 0.50 mm (0.020 in.)
oversize pistons. Always use new piston rings when
installing pistons. Never use old rings.
Some important points to remember when servicing
piston rings:
1. Cylinder bore must be deglazed before service ring
sets are used.
2. If cylinder bore does not need reboring and if old
piston is within wear limits and free of score or scuff
marks, old piston may be reused.
3. Remove old rings and clean up grooves. Never
reuse old rings.
4. Before installing new rings on piston, place top two
rings, each in turn, in its running area in cylinder
bore and check end gap. Compare ring gap to
tolerances listed in Specifi cations.
5. After installing new compression (top and middle)
rings on piston, check piston-to-ring side clearance.
Compare clearance to tolerance listed in
Specifi cations. If side clearance is greater than
specifi ed, a new piston must be used.
69
Disassembly/Inspection and Service
24 690 30 Rev. G KohlerEngines.com
To install new piston rings, proceed as follows:
1. Oil control ring (bottom groove): Install expander and
then rails. Make sure ends of expander are not
overlapped.
2. Middle compression ring (center groove): Install
center ring using a piston ring installation tool. Make
sure identifi cation mark is up or dye colored stripe (if
contained) is to left of end gap.
3. Top compression ring (top groove): Install top ring
using a piston ring expender. Make sure
identifi cation mark is up or dye colored stripe (if
contained), left of end gap.
Install New Piston Rings
Piston Ring Orientation
10°
10°
F
A
B
C
D
E
A
Top Oil Ring Rail
Gap
B
Bottom Oil Ring Rail
Gap
C
Intermediate Ring
Gap
D
Oil Ring Expander
Gap
E Top Ring Gap F FLY Stamp
NOTE: Rings must be installed correctly. Ring
installation instructions are usually included with
new ring sets. Follow instructions carefully. Use
a piston ring expander to install rings. Install
bottom (oil control) ring fi rst and top
compression ring last.
To install new piston rings, proceed as follows:
1. Oil control ring (bottom groove): Install expander and
then rails. Make sure ends of expander are not
overlapped.
2. Middle compression ring (center groove): Install
center ring using a piston ring installation tool. Make
sure identifi cation mark is up or colored dye stripe
(if contained), is to left of end gap.
3. Top compression ring (top groove): Install top ring
using a piston ring expander. Make sure
identifi cation mark is up or colored dye stripe
(if contained), is to left of end gap.
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Disassembly/Inspection and Service
KohlerEngines.com 24 690 30 Rev. G
Carefully pull crankshaft from crankcase. Note thrust
washers and shims if used.
Inspect gear teeth of crankshaft. If teeth are badly worn,
chipped, or some are missing, replacement of crankshaft
will be necessary.
Inspect crankshaft bearing surfaces for scoring,
grooving, etc. Some engines have bearing inserts in
crankshaft bore of closure plate and/or crankcase.
Do not replace bearings unless they show signs of
damage or are out of running clearance specifi cations. If
crankshaft turns easily and noiselessly, and there is no
evidence of scoring, grooving, etc., on races or bearing
surfaces, bearings can be reused.
Inspect crankshaft keyways. If they are worn or chipped,
replacement of crankshaft will be necessary.
Inspect crankpin for score marks or metallic pickup.
Slight score marks can be cleaned with crocus cloth
soaked in oil. If wear limits, as stated in Specifi cations
and Tolerances are exceeded, it will be necessary to
either replace crankshaft or regrind crankpin to 0.25 mm
(0.010 in.) undersize. If reground, a 0.25 mm (0.010 in.)
undersize connecting rod (big end) must then be used to
achieve proper running clearance. Measure crankpin for
size, taper, and out-of-round.
Connecting rod journal can be ground one size under.
When grinding a crankshaft, grinding stone deposits
can get caught in oil passages, which could cause
severe engine damage. Removing crankpin plug when
crankshaft is ground provides easy access for removing
any grinding deposits collected in oil passages.
Use following procedure to remove and replace plug.
Procedure to Remove Crankshaft Plug:
1. Drill a 3/16 in. hole through plug in crankshaft.
2. Thread a 3/4 in. or 1 in. long self-tapping screw with
a fl at washer into drilled hole. Flat washer must be
large enough to seat against shoulder of plug bore.
3. Tighten self-tapping screw until it draws plug out of
crankshaft.
Procedure to Install New Plug:
Use 1 single cylinder camshaft pin as a driver and tap
plug into plug bore until it seats at bottom of bore. Make
sure plug is tapped in evenly to prevent leakage.
Remove Governor Cross Shaft
1. Remove hitch pin and plain washer, or retainer and
nylon washer from governor cross shaft.
2. Pull cross shaft with small washer out through inside
of crankcase.
Connecting Rods
Off set, stepped-cap connecting rods are used in all
these engines.
Inspection and Service
Check bearing area (big end) for excessive wear,
score marks, running and side clearances (refer to
Specifi cations). Replace rod and cap if scored or
excessively worn.
Service replacement connecting rods are available in
STD crankpin size and 0.25 mm (0.010 in.) undersize.
An 0.25 mm (0.010 in.) undersized rod can be identifi ed
by a drilled hole located in lower end of rod shank.
Always refer to appropriate parts information to ensure
correct replacements are used.
Remove Crankshaft
Inspection and Service
Crankshaft Components and Details
A
B
C
D
A Self-Tapping Screw B Flat Washer
C Plug D Crankshaft
E
G
F
H
E
Fillet Must Blend Smoothly with Bearing Journal
Surface
F High Point from Fillet Intersections
G 45° Minimum
H This Fillet Area Must Be Completely Smooth
NOTE: If crankpin is reground, visually check to ensure
fi llet blends smoothly with crankpin surface.
NOTE: To prevent repeat failures, camshaft and
crankshaft should always be replaced as a set.
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24 690 30 Rev. G KohlerEngines.com
Governor Cross Shaft Oil Seal
Cross Shaft Oil Seal Details
B
A
A 2.0 mm (0.0787 in.)
B Governor Cross Shaft Seal
If governor cross shaft seal is damaged and/or leaks,
replace it using following procedure.
Remove oil seal from crankcase and replace it with a
new one. Install new seal to depth shown using a seal
installer.
Remove Flywheel End Oil Seal
Remove oil seal from crankcase.
Crankcase
Inspection and Service
Check all gasket surfaces to make sure they are free of
gasket fragments. Gasket surfaces must also be free of
deep scratches or nicks.
Inspect main bearing (if equipped) for wear or damage.
Replace crankcase using a miniblock or short block as
required.
Check cylinder bore wall for scoring. In severe cases,
unburned fuel can cause scuffi ng and scoring of cylinder
wall. It washes necessary lubricating oils off piston and
cylinder wall. As raw fuel seeps down cylinder wall,
piston rings make metal to metal contact with wall.
Scoring of cylinder wall can also be caused by localized
hot spots resulting from blocked cooling fi ns or from
inadequate or contaminated lubrication.
If cylinder bore is badly scored, excessively worn,
tapered, or out-of-round, resizing is necessary. Use an
inside micrometer to determine amount of wear (refer
to Specifi cations), then select nearest suitable oversize
of either 0.25 mm (0.010 in.) or 0.50 mm (0.020 in.).
Resizing to one of these oversizes will allow usage of
available oversize piston and ring assemblies. First,
resize using a boring bar, then follow these procedures
for honing cylinder.
Honing
Detail
A
A 23°-33° Crosshatch
NOTE: Some CH25 engines feature POWER-BORE
™
cylinders a special patented nickel-silicone
plating process for increased power, superior oil
control, reduced exhaust emission, and virtually
permanent cylinder life. POWER-BORE
™
cylinders cannot be resized or honed as
described in these procedures. If a plated
cylinder bore is damaged or out of specifi cation,
use a new miniblock or short block to repair
engine. Use following procedure for crankcases
with a cast iron sleeve.
NOTE: Kohler pistons are custom-machined to exacting
tolerances. When oversizing a cylinder, it should
be machined exactly 0.25 mm (0.010 in.) or 0.50
mm (0.020 in.) over new diameter (refer to
Specifi cations). A corresponding oversize Kohler
replacement piston will then fi t correctly.
While most commercially available cylinder hones can
be used with either portable drills or drill presses, use
of a low speed drill press is preferred as it facilitates
more accurate alignment of bore in relation to crankshaft
crossbore. Honing is best accomplished at a drill speed
of about 250 RPM and 60 strokes per minute. After
installing coarse stones in hone, proceed as follows:
1. Lower hone into bore and after centering, adjust so
stones are in contact with cylinder wall. Use of a
commercial cutting-cooling agent is recommended.
2. With lower edge of each stone positioned even with
lowest edge of bore, start drill and honing process.
Move hone up and down while resizing to prevent
formation of cutting ridges. Check size frequently.
3. When bore is within 0.064 mm (0.0025 in.) of
desired size, remove coarse stones and replace
them with burnishing stones. Continue with
burnishing stones until bore is within 0.013 mm
(0.0005 in.) of desired size and then use fi nish
stones (220-280 grit) and polish bore to its fi nal size.
A crosshatch should be observed if honing is done
correctly. Crosshatch should intersect at
approximately 23°-33° off horizontal. Too fl at an
angle could cause rings to skip and wear
excessively, and too steep an angle will result in high
oil consumption.
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Disassembly/Inspection and Service
KohlerEngines.com 24 690 30 Rev. G
4. After resizing, check bore for roundness, taper, and
size. Use an inside micrometer, telescoping gauge,
or bore gauge to take measurements. These
measurements should be taken at 3 locations in
cylinder–at top, middle, and bottom. There are 2
measurements that should be taken (perpendicular
to each other) at all 3 locations.
Clean Cylinder Bore After Honing
Proper cleaning of cylinder walls following boring and/
or honing is very critical to a successful overhaul.
Machining grit left in cylinder bore can destroy an engine
in less than one hour of operation after a rebuild.
Final cleaning operation should always be a thorough
scrubbing with a brush and hot, soapy water. Use a
strong detergent capable of breaking down machining
oil while maintaining a good level of suds. If suds break
down during cleaning, discard dirty water and start again
with more hot water and detergent. Following scrubbing,
rinse cylinder with very hot, clear water, dry it completely,
and apply a light coating of engine oil to prevent rusting.
Measuring Piston-to-Bore Clearance
Piston Detail
A
A 6 mm (0.2362 in.)
NOTE: Do not use a feeler gauge to measure piston-to-
bore clearance–it will yield inaccurate
measurements. Always use a micrometer.
Before installing piston into cylinder bore, it is
necessary clearance be accurately checked. This step
is often overlooked, and if clearances are not within
specifi cations, engine failure will usually result.
Use following procedure to accurately measure piston-
to-bore clearance:
1. Use a micrometer and measure diameter of piston
6 mm (0.2362 in.) above bottom of piston skirt and
perpendicular to piston pin.
2. Use an inside micrometer, telescoping gauge, or
bore gauge and measure cylinder bore. Take
measurement approximately 63.5 mm (2.5 in.) below
top of bore and perpendicular to piston pin.
3. Piston-to-bore clearance is diff erence between bore
diameter and piston diameter (step 2 minus step 1).
Crankcase Components
A
Q
P
H
F
E
B
A
C
D
G
I
L
J
O
N
M
R
K
Y
S
V
U
T
W
X
A Oil Seal B Closure Plate (Style A) C
Gerotor Gears
(Style A)
D Dipstick Tube
E
Oil Pick-Up Tube
(Style A)
F
Oil Pump Assembly
(Style A)
G Governor Gear Shaft H Governor Gear
I Camshaft J Piston Pin K Piston Ring Set L Piston Pin Retainer
M Piston N Connecting Rod O
Connecting Rod End
Cap
P Crankshaft
Q Oil Drain Plug R Governor Cross Shaft S Closure Plate (Style B) T
Outer Gerotor Gear
(Style B)
U Ball (Style B) V Spring (Style B) W
Oil Pump Cover O-ring
(Style B)
X
Oil Pump Assembly
(Style B)
Y
Oil Pick-Up Tube
(Style B)
NOTE: Make sure engine is assembled using all
specifi ed torque values, tightening sequences
and clearances. Failure to observe specifi cations
could cause severe engine wear or damage.
Always use new gaskets. Apply a small amount
of oil to threads of critical fasteners before
assembly, unless a sealant or Loctite
®
is
specifi ed or preapplied.
Make sure all traces of any cleaner are removed before
engine is assembled and placed into operation. Even
small amounts of these cleaners can quickly break down
lubricating properties of engine oil.
Check closure plate, crankcase, cylinder heads, and
valve covers to be certain all old sealing material has
been removed. Use gasket remover, lacquer thinner, or
paint remover to remove any remaining traces. Clean
surfaces with isopropyl alcohol, acetone, lacquer thinner,
or electrical contact cleaner.
Install Flywheel End Oil Seal
1. Make sure seal bore of crankcase is clean and free
of any nicks or burrs.
2. Apply a light coat of clean engine oil to outside
diameter of oil seal.
3. Drive oil seal into crankcase using a seal driver.
Make sure oil seal is installed straight and true in
bore and tool bottoms against crankcase.
Reassembly
7324 690 30 Rev. G KohlerEngines.com
Install Governor Cross Shaft
1. Lubricate governor cross shaft bearing surfaces in
crankcase with engine oil.
2. Slide small lower washer onto governor cross shaft
and install cross shaft from inside of crankcase.
3. 6 mm governor shaft: Install plain washer and then
insert hitch pin into smaller, lower hole of governor
cross shaft.
8 mm governor shaft: Install nylon washer onto
governor cross shaft, then start push-on retaining
ring. Hold cross shaft up in position, place a
0.50 mm (0.020 in.) feeler gauge on top of nylon
washer, and push retaining ring down shaft to
secure. Remove feeler gauge, which will have
established proper end play.
Install Crankshaft
Carefully slide fl ywheel end of crankshaft through main
bearing in crankcase.
Install Connecting Rods with Pistons and Rings
Piston and Connecting Rod Details
A
B
A Cylinder 1 B Cylinder 2
Connecting Rod Bolt Details
A
B
C
Type Torque
A 8 mm Straight Shank 22.7 N·m (200 in. lb.)
B 8 mm Step-Down 14.7 N·m (130 in. lb.)
C 6 mm Straight Shank 11.3 N·m (100 in. lb.)
NOTE: Cylinders are numbered on crankcase. Make
sure to install piston, connecting rod and end
cap into its appropriate cylinder bore as
previously marked at disassembly. Do not mix
end caps and connecting rods.
NOTE: Proper orientation of piston/connecting rod
assemblies inside engine is extremely important.
Improper orientation can cause extensive wear
or damage. Be certain pistons and connecting
rods are assembled exactly as shown.
NOTE: Align chamfer of connecting rod with chamfer of
its mating end cap. When installed, fl at faces of
connecting rods should face each other. Faces
with raised rib should be toward outside.
1. If piston rings were removed, see Disassembly/
Inspection and Service procedure to install new
rings.
2. Lubricate cylinder bore, piston, and piston rings with
engine oil. Compress rings of piston 1 using a piston
ring compressor.
3. Lubricate crankshaft journals and connecting rod
bearing surfaces with engine oil.
4. Make sure FLY stamping on piston is facing towards
fl ywheel side of engine. Use a hammer with a rubber
grip and gently tap piston into cylinder. Be careful oil
ring rails do not spring free between bottom of ring
compressor and top of cylinder.
5. Install inner rod cap to connecting rod using screws.
Three diff erent types of connecting rod bolts have
been used and each has a diff erent torque value. If
8 mm straight shank type bolts are used, torque in
increments to 22.7 N·m (200 in. lb.). If 8 mm step-
down bolts are used, torque in increments to
14.7 N·m (130 in. lb.). If 6 mm straight shank bolts
are used, torque in increments to 11.3 N·m
(100 in. lb.). Illustrated instructions are provided in
service rod package.
6. Repeat above procedure for other connecting rod
and piston assembly.
Install Camshaft
1. Liberally apply camshaft lubricant to each cam lobe.
Lubricate camshaft bearing surfaces of crankcase
and camshaft with engine oil.
2. Position timing mark of crankshaft gear at 12 o’clock
position.
3. Turn governor cross shaft clockwise until lower end
of shaft contacts cylinder. Make sure cross shaft
remains in this position while installing camshaft.
4. Slide camshaft into bearing surface of crankcase,
positioning timing mark of camshaft gear at 6 o’clock
position. Make sure camshaft gear and crankshaft
gear mesh, with both timing marks aligned.
Reassembly
74 24 690 30 Rev. GKohlerEngines.com
Determining Camshaft End Play
1. Install shim removed during disassembly onto
camshaft.
2. Position camshaft end play checking tool on
camshaft.
3. Apply pressure on camshaft end play checking tool
(pushing camshaft toward crankshaft). Use a feeler
gauge to measure camshaft end play between shim
spacer and checking tool. Camshaft end play should
be 0.076/0.127 mm (0.003/0.005 in.).
4. If camshaft end play is not within specifi ed range,
remove checking tool and replace shim as
necessary.
Several color coded shims are available:
White: 0.69215/0.73025 mm (0.02725/0.02875 in.)
Blue: 0.74295/0.78105 mm (0.02925/0.03075 in.)
Red: 0.79375/0.83185 mm (0.03125/0.03275 in.)
Yellow: 0.84455/0.88265 mm (0.03325/0.03475 in.)
Green: 0.89535/0.99345 mm (0.03525/0.03675 in.)
Gray: 0.94615/0.98425 mm (0.03725/0.03875 in.)
Black: 0.99695/1.03505 mm (0.03925/0.04075 in.)
5. Reinstall end play checking tool and recheck end
play.
Oil Pump Assembly
Oil pump is mounted inside closure plate. If service
was required, and oil pump was removed, refer to
Disassembly/Inspection and Service.
Governor Gear Assembly
Governor gear assembly is located inside closure plate.
If service was required, and governor was removed,
refer to Disassembly/Inspection and Service.
Thrust Bearing, Washer and Shim
Thrust Bearing, Washer, and Shim Sequence
D
A
B
C
E
A Thrust Shim B Thrust Washer
C
Needle Thrust
Bearing
D Bearing Race
E Closure Plate
Some specifi cations use a needle type thrust bearing,
thrust washer and shim spacer to control end play of
crankshaft. If these items are noted during disassembly,
make sure they are reinstalled in sequence shown. A
diff erent procedure will have to be followed to check and
adjust crankshaft end play on these models.
Race for thrust bearing presses loosely into closure
plate. If it is not already installed, push it into crankshaft
bore inside closure plate. Pack thrust bearing with heavy
grease and stick bearing into race. Wipe some grease
on face of thrust washer and stick it onto thrust bearing.
Wipe some grease on face of original shim spacer and
stick it onto thrust washer.
Install closure plate onto crankcase without applying
RTV sealant and secure it with only two or three
fasteners at this time. Use a dial indicator to check
crankshaft end play. End play should be 0.070/1.190
mm (0.0028/0.0468 in.), except for CH25 engines
below Serial No. 2403500008 end play should be
0.050/0.75 mm (0.0020/0.0295 in.). Shim spacers are
available in three color coded thicknesses listed below if
adjustment is needed.
Crankshaft End Play Shims
Green: 0.8366-0.9127 mm
(0.8750 mm/0.034 in. Nominal)
Yellow: 1.0652-1.1414 mm
(1.1033 mm/0.043 in. Nominal)
Red: 1.2938-1.3700 mm
(1.3319 mm/0.052 in. Nominal)
Reassembly
7524 690 30 Rev. G KohlerEngines.com
Remove closure plate. If end play requires adjustment,
remove original spacer and install appropriate size shim
spacer in its place. Then follow procedure under Install
Closure Plate Assembly.
Install Closure Plate Oil Seal
Oil Seal Depth
A
B
A Oil Seal B
Seal Depth
8.0 mm (0.314 in.)
1. Check to make sure there are no nicks or burrs in
crankshaft bore of closure plate.
2. Apply a light coat of engine oil to outside diameter of
oil seal.
3. Drive oil seal into closure plate using a seal driver.
Make sure oil seal is installed straight and true in
bore to depth shown.
Install Closure Plate Assembly
Sealant Pattern and Torque Sequence
1
10
8
6
42
9
7
5
3
RTV sealant is used as a gasket between closure
plate and crankcase. Always use fresh sealant. Using
outdated sealant can result in leakage.
1. Be sure sealing surfaces have been cleaned and
prepared. Install a new O-ring in closure plate.
2. Check to make sure there are no nicks or burrs on
sealing surfaces of closure plate or crankcase.
3. Apply a 1.5 mm (1/16 in.) bead of sealant to sealing
surface of closure plate.
4. Make sure end of governor cross shaft is lying
against bottom of cylinder 1 inside crankcase.
5. Install closure plate to crankcase. Carefully seat
camshaft and crankshaft into their mating bearings.
Rotate crankshaft slightly to help engage oil pump
and governor gear meshes.
6. Install screws securing closure plate to crankcase.
Torque fasteners to 24.4 N·m (216 in. lb.) following
sequence. On some engines one mounting screw is
plated. Plated screw is typically installed in hole
location 6. For LPG engines, install vaporizer
bracket to hole locations 8 and 10.
Reassembly
76 24 690 30 Rev. GKohlerEngines.com
NOTE: Make sure fl ywheel key is installed properly in
keyway. Flywheel can become cracked or
damaged if key is not properly installed.
1. Install woodruff key into keyway of crankshaft. Make
sure key is properly seated and parallel with shaft
taper.
2. Install fl ywheel onto crankshaft being careful not to
shift woodruff key.
3. Install screw and washer.
4. Use a fl ywheel strap wrench or holding tool to hold
fl ywheel. Torque screw securing fl ywheel to
crankshaft to 66.4 N·m (49 ft. lb.).
Install Flywheel Fan
NOTE: Position ears located at rear perimeter of fan in
recesses of fl ywheel.
1. Install fan onto fl ywheel using four screws.
2. Torque screws to 9.9 N·m (88 in. lb.).
Install Stator and Backing Plates
1. Apply pipe sealant with Tefl on
®
(Loctite
®
PST
®
592™
Thread Sealant or equivalent) to stator mounting
holes.
2. Position stator aligning mounting holes so leads are
at bottom, towards crankcase.
3. Install and torque screws to 6.2 N·m (55 in. lb.).
4. Route stator leads in crankcase channel, then install
backing plates and stator wire bracket (if used).
Secure using screws. Torque screws to 7.3 N·m
(65 in. lb.).
Install Flywheel
CAUTION
Damaging Crankshaft and Flywheel can
cause personal injury.
Using improper procedures can lead to broken
fragments. Broken fragments could be thrown from
engine. Always observe and use precautions and
procedures when installing fl ywheel.
NOTE: Before installing fl ywheel make sure crankshaft
taper and fl ywheel hub are clean, dry, and
completely free of any lubricants. Presence of
lubricants can cause fl ywheel to be over
stressed and damaged when screw is torqued to
specifi cations.
Flywheel/Ignition Components
F
G
E
C
K
L
O
M
N
H
P
B
I
D
J
A
A Debris Screen B Fan C Flywheel Screw D Washer
E Flywheel F Magnet G Stator H Ignition Module
I Backing Plate J Woodruff Key K Spring Washer L Spacer
M Ring Support N Metal Debris Screen O Washer P
Metal Debris Screen
Assembly
Reassembly
7724 690 30 Rev. G KohlerEngines.com
Install Hydraulic Lifters
NOTE: Hydraulic lifters should always be installed in
same position as before disassembly. Exhaust
lifters are located on output shaft side of engine
while intake lifters are located on fan side of
engine. Cylinder numbers are embossed on top
of crankcase and each cylinder head.
1. Refer to Disassembly/Inspection and Service for
lifter preparation (bleed down) procedures.
2. Apply camshaft lubricant to bottom surface of each
lifter. Lubricate hydraulic lifters and lifter bores in
crankcase with engine oil.
Cylinder Head Components
B
C
D
E
G
K
F
H
I
J
L
M
N
O
P
A
A Valve B Stud C Gasket D Spark Plug
E Cap F Valve Stem Seal G Hydraulic Lifter H Retainer
I Valve Spring J Valve Spring Retainer K Push Rod L Valve Keeper
M Rocker Arm N Rocker Arm Pivot O Valve Cover O-ring P Valve Cover
Install Plastic Debris Screen
CAUTION
Failure to utilize or reassemble debris screen
as designed could result in debris screen
failure and serious personal injury.
If engine has a plastic debris screen, snap screen onto
fan. Due to possibility of damaging posts during removal,
install retainers on diff erent posts from which they were
removed. Start retainers by hand, then push them down
with a 13 mm (1/2 in.) socket until they lock. If engine
has a metal screen, it will be installed later.
Install Supports for Metal Debris Screen
1. If a metal debris screen is used, with threaded
individual supports, install a spacer washer on
external threads. Apply Loctite
®
242
®
(removable)
onto threads. Install four supports.
2. Tighten supports with a torque wrench to 9.9 N·m
(88 in. lb.). Debris screen will be installed to supports
after blower housing is in place.
3. Note mark or tag identifying hydraulic lifters as either
intake or exhaust and cylinder 1 or cylinder 2. Install
hydraulic lifters into their appropriate location in
crankcase. Do not use a magnet.
Valve Stem Seals
These engines use valve stem seals on intake valves
and occasionally on exhaust valves. Always use a new
seal whenever valve is removed or if seal is deteriorated
or damaged in any way. Never reuse an old seal.
Reassembly
78 24 690 30 Rev. GKohlerEngines.com
Assemble Cylinder Heads
Prior to installation, lubricate all components with engine
oil, paying particular attention to lip of valve stem seal,
valve stems and valve guides. Install in order listed
below using a valve spring compressor.
● Intake and exhaust valves.
● Valve spring caps.
● Valve springs.
● Valve spring retainers.
● Valve spring keepers.
Install Cylinder Heads
Cylinder Head Torque Sequence
1
1
2
1
4
4
2
2
3
3
NOTE: Cylinder heads must be attached with original
type of mounting hardware, using either screws,
or mounting studs with nuts and washers. Heads
are machined diff erently for studs than for
screws, so fastening method cannot be altered
unless heads are being replaced. Do not
intermix components.
Heads secured with screws:
NOTE: Match numbers embossed on cylinder heads
and crankcase.
1. Check to make sure there are no nicks or burrs on
sealing surfaces of cylinder head or crankcase.
2. Install a new cylinder head gasket, (with printing up).
3. Install cylinder head and lightly lubricate threads of
bolts with engine oil, but be careful not to get any oil
on gasket sealing surfaces. Thread bolts in until
fi nger tight.
4. Torque screws in two stages; fi rst to 22.6 N·m
(200 in. lb.), fi nally to 41.8 N·m (370 in. lb.), following
sequence shown.
Heads secured with mounting studs, nuts, and
washers:
1. Check to make sure there are no nicks or burrs on
sealing surfaces of cylinder head or crankcase.
2. If all studs were left intact, go to Step 5. If any studs
were disturbed or removed, install new studs as
described in Step 3. Do not use/reinstall any
loosened or removed studs.
3. Install new mounting stud(s) into crankcase.
a. Thread and lock two mounting nuts together on
smaller diameter threads.
b. Thread opposite end of stud with preapplied
locking compound into crankcase until specifi ed
height from crankcase surface is achieved.
When threading in studs, use a steady tightening
motion without interruption until proper height is
obtained. Otherwise, frictional heat from
engaging threads may cause locking compound
to set up prematurely.
Studs closest to lifters must have an exposed
height of 75 mm (2 15/16 in.).
Studs furthest from lifters must have an exposed
height of 69 mm (2 3/4 in.).
c. Remove nuts and repeat procedure as required.
4. Install cylinder head. Match numbers on cylinder
heads and crankcase. Make sure head is fl at on
gasket and dowel pins.
5. Lightly lubricate exposed (upper) threads of studs
with engine oil. Install a fl at washer and nut onto
each mounting stud. Torque nuts in two stages; fi rst
to 16.9 N·m (150 in. lb.), fi nally to 35.5 N·m
(315 in. lb.), following sequence shown.
Install Push Rods and Rocker Arms
NOTE: Push rods should always be installed in same
position as before disassembly.
NOTE: Two diff erent screws have been used to secure
rocker arms/pivots. Black screws are used with
heads that have a rocker pivot hole depth of
approximately 21 mm (0.83 in.). Silver screws
are used with heads that have a rocker pivot
hole depth of approximately 35 mm (1.38 in.).
Early models used hollow push rods with special rocker
arms. They are not interchangeable with later/current
style solid push rods and associated rocker arms. Do
not mix these. A replacement kit is available with solid
components.
1. Note mark or tag identifying push rod as either
intake or exhaust and cylinder 1 or 2. Dip ends of
push rods in engine oil and install, making sure each
push rod ball seats in its hydraulic lifter socket.
2. Apply grease to contact surfaces of rocker arms and
rocker arm pivots. Install rocker arms and rocker arm
pivots on one cylinder head, and start two screws.
3. Torque black screws to 18.1 N·m (160 in. lb.).
Torque silver screws to 13.6 N·m (120 in. lb.).
Repeat for other rocker arm.
4. Use a spanner wrench or rocker arm lifting tool to lift
rocker arms and position push rods underneath.
5. Repeat above steps for remaining cylinder. Do not
interchange parts from cylinder heads.
6. Rotate crankshaft to check for free operation of
valve train. Check clearance between valve spring
coils at full lift. Minimum allowable clearance is
0.25 mm (0.010 in.).
Check Assembly
Rotate crankshaft a minimum of two revolutions to check
longblock assembly and overall proper operation.
Reassembly
7924 690 30 Rev. G KohlerEngines.com
Install Spark Plugs
1. Check gap using wire feeler gauge. Adjust gap to
0.76 mm (0.030 in.) for all except NG with CD fi xed
timing or 0.51 mm (0.020 in.) for NG with CD fi xed
timing.
2. Install plug into cylinder head.
3. Torque plug to 27 N·m (20 ft. lb.).
Install Ignition Modules
1. Rotate fl ywheel to position magnet away from
ignition module bosses.
2. On engines equipped with SMART-SPARK
™
both
modules are installed with tabs out.
On engines not equipped with SMART-SPARK
™
modules are installed on cylinder 1 with single kill
tab should be towards you (out) and on cylinder 2
with single kill tab away from you (in).
3. Install each ignition module to crankcase bosses
with screws (hex fl ange or allen head, based on
model). Slide modules up as far away from fl ywheel
as possible and snug screws to hold them in
position.
4. Rotate fl ywheel to position magnet directly under
one ignition module.
5. Insert a 0.30 mm (0.012 in.) fl at feeler gauge
between magnet and ignition module. Loosen
screws enough to allow magnet to pull module down
against feeler gauge.
6. Torque screws to 4.0-6.2 N·m (35-55 in. lb.).
7. Repeat steps 4 through 6 for other ignition module.
8. Rotate fl ywheel back and forth checking for
clearance between magnet and ignition modules.
Make sure magnet does not strike modules. Check
gap with a feeler gauge and readjust if necessary.
Final air gap: 0.280/0.330 mm (0.011/0.013 in.).
Install Intake Manifold
Torque Sequence
1
2
3
4
NOTE: If wires were disconnected from ignition modules
on engines with SMART-SPARK
™
, reattach
leads and seal base of terminal connectors with
GE/Novaguard G661 or equivalent dielectric
compound. Beads should overlap between
terminals to form a solid bridge of compound. Do
not put any compound inside terminals. 24 584
15-S ignition modules have a separator barrier
between terminals. On these modules, seal base
of terminals, but it is not necessary to have
overlapping beads of sealant between
connections.
1. Install intake manifold and new gaskets or O-rings
(plastic manifold), with wiring harness attached, to
cylinder heads. Slide any wiring harness clips onto
appropriate bolts before installing. Make sure
gaskets are in proper orientation. Torque screws in
two stages, fi rst to 7.4 N·m (66 in. lb.), then to
9.9 N·m (88 in. lb.), using sequence shown.
2. Connect kill lead to tab terminal on standard ignition
modules.
Reassembly
80 24 690 30 Rev. GKohlerEngines.com
External Engine Components
G
X
V
W
D
A
C
F
E
B
H
L
I
K
J
N
M
O
H
U
E
T
R
S
S
R
Q
Q
P
A Vaporizer B Lock-off /Filter C Regulator D Carburetor
E Gasket F Intake Manifold G Plastic Intake Manifold H Outer Baffl e
I Inner Baffl e J Breather Reed K Breather Gasket L Breather Cover
M Breather Tube N Oil Sentry
™
O Filter P Air Cleaner
Q Oil Filter R Nipple S Oil Cooler T Electric Starter
U Lifting Bracket V Fixed Guard W Blower Housing X Debris Shield
Reassembly
8124 690 30 Rev. G KohlerEngines.com
3. Position outer baffl es and loosely start mounting
screws. M6 screws go into back of cylinders. Short
M5 screws go into lower holes closest to blower
housing. Short screw on oil fi lter side is also used to
mount wire harness clip. Be sure any wire harnesses
or leads are routed out through proper off sets or
notches, so they will not be pinched between blower
housing and baffl es.
4. If rectifi er-regulator was not removed, attach ground
wire or metal grounding bracket for rectifi er-
regulator, using silver colored screw and washer, to
lower blower housing hole.
5. Tighten all shrouding fasteners. Torque blower
housing screws to 6.2 N·m (55 in. lb.) in a new hole,
or to 4.0 N·m (35 in. lb.) in a used hole. Torque
shorter M5 side baffl e screws to 4.0 N·m (35 in. lb.).
Torque upper M5 side baffl e screws (into cylinder
head) to 6.2 N·m (55 in. lb.) in a new hole, or to
4.0 N·m (35 in. lb.) in a used hole. Torque two rear
M6 baffl e mounting screws to 10.7 N·m (95 in. lb.) in
a new hole, or to 7.3 N·m (65 in. lb.) in a used hole.
6. If an overlapping style fl ywheel screen is used,
attach it to supports or fl ywheel. For a metal fl ywheel
screen, apply Loctite
®
242
®
to screw threads (M6)
and torque to 9.9 N·m (88 in. lb.). Torque plastic
screen mounting screws (M4) to 2.2 N·m (20 in. lb.).
7. Torque breather cover screws to 11.3 N·m (100 in.
lb.) into new holes or 7.3 N·m (65 in. lb.) into used
holes in sequence shown. Note fi rst screw is torqued
a second time.
Reconnect Rectifi er-Regulator
1. Install rectifi er-regulator in blower housing, if
removed previously, then connect rectifi er-regulator
ground lead with washer and silver screw through
eyelet. If a grounding bracket is used, secure with
lower mounting screw and washer, against outer
side of rectifi er-regulator.
2. Install B+ terminal/lead into center position of
rectifi er-regulator plug and connect plug to rectifi er-
regulator.
SMART-SPARK
™
Module
On engines with SMART-SPARK
™
, reinstall SAM Module
to blower housing or cylinder baffl e. Do not overtighten
retaining screws.
Install Electric Starter Motor
NOTE: If engine uses a side mount muffl er on starter
side, be sure to tie wires close to starter to avoid
contact with hot exhaust parts.
1. Install starter motor using two screws. Some inertia-
drive starters have a pinion cover and spacers on
starter bolts.
2. Torque screws to 15.3 N·m (135 in. lb.).
3. On models with a solenoid shift starter, connect
leads to solenoid.
Install Breather Cover and Inner Baffl es
Breather Cover Details and Torque Sequence
A
A
1
2
3
4
A Install These Screws First
RTV sealant was used on early models between
breather cover and crankcase. A gasket with imprinted
sealant beads is now used and recommended. Install as
follows:
1. Be sure sealing surfaces of crankcase and breather
cover are clean of old gasket material or RTV
sealant. Do not scrape surfaces as this could result
in leakage.
2. Check to make sure there are no nicks or burrs on
sealing surfaces.
3. Install breather reed and breather reed retainer onto
crankcase and secure with screw. Hold assembly in
line when tightening. Torque screw to 3.9 N·m
(35 in. lb.).
4. Insert breather fi lter into position in crankcase. Make
sure no fi lter strands are on sealing surface.
5. Install new breather gasket.
6. Carefully position breather cover on crankcase.
Install fi rst two screws at positions shown and fi nger
tighten at this time.
7. Install inner baffl es using two remaining screws and
fi nger tighten. Do not torque screws at this time; they
will be tightened after blower housing and outer
baffl es are installed.
Install Blower Housing and Outer Baffl es
NOTE: Do not completely tighten screws until all items
are installed to allow shifting for hole alignment.
1. Connect plug to key switch in blower housing (if
equipped).
2. Slide blower housing into position over front edge of
inner baffl es. Start a few screws to hold it in place.
Make sure ground lead and oil pressure switch leads
are accessible and in proper position.
Reassembly
82 24 690 30 Rev. GKohlerEngines.com
Install Carburetor (Mechanical Governor)
WARNING
Explosive Fuel can cause fi res and severe
burns.
If a gaseous odor is detected, ventilate area
and contact an authorized service technician.
LPG is extremely fl ammable and is heavier than air
and tends to settle in low areas where a spark or fl ame
could ignite gas. Do not start or operate this engine
in a poorly ventilated area where leaking gas could
accumulate and endanger safety of persons in area.
NG is extremely fl ammable, is lighter than air, and
rises. Do not start or operate this engine in a poorly
ventilated area where leaking gas could accumulate
and endanger safety of persons in area.
To ensure personal safety, installation and repair of
LPG/NG fuel supply systems must be performed only
by qualifi ed LPG/NG system technicians. Improperly
installed and maintained LPG/NG equipment could
cause fuel supply system or other components to
malfunction, causing gas leaks.
Observe federal, state and local laws governing LPG/
NG fuel, storage, and systems.
1. Install a new carburetor gasket. Make sure all holes
align and are open.
2. Install carburetor, throttle linkage and governor lever
as an assembly. If a plastic intake manifold is used
attach ground lead to carburetor mounting screw.
3. Torque carburetor mounting screws or nuts to
6.2-7.3 N·m (55-65 in. lb.).
Install Carburetor and Electronic Governor
A
F
C
H
B
E
D
G
A Carburetor Fitting B Carburetor
C Flywheel Side D
Carburetor Throttle
Lever
E Bushing F Throttle Linkage
G
Electronic Governor
Assembly
H
Electronic Governor
Connector
1. Install a new carburetor gasket. Make sure all holes
align and are open.
2. Place carburetor in position on intake manifold/
carburetor gasket, then start screws. While holding
carburetor towards fl ywheel side of engine, torque
screws to 6.2-7.3 N·m (55-65 in. lb.).
3. Reconnect fuel hose to carburetor fi tting and secure
hose clamp.
4. Reconnect throttle linkage in carburetor throttle lever
and secure with bushing.
5. Position electronic governor assembly on crankcase
and start screws but do not tighten them.
6. Lightly hold throttle lever in idle position. Use a
straight edge ruler and adjust governor assembly
location to measure 2.54 cm (1 inch) from back of
throttle linkage. Torque screws to 7.3 N·m (65 in. lb.).
7. Connect electronic governor to wiring harness.
Install LPG/NG Components
1. Install regulator bracket to crankcase with screws
and torque to 22.6 N·m (200 in. lb.).
2. Install regulator to bracket with screws and torque to
24.4 N·m (216 in. lb.). Attach vacuum line and fuel
lines to regulator.
3. Secure vaporizer to bracket (if equipped) with 2
screws. Torque 3/8 in. screw to 29.4 N·m (260 in. lb.)
and 1/4 in. screw to 7.9 N·m (70 in. lb.).
4. Attach fuel lines from regulator to lock-off /fi lter and
carburetor.
Reassembly
8324 690 30 Rev. G KohlerEngines.com
Governor Lever Hole Position (6 mm)
H
A
G
F
E
D
C
B
A Governor Lever B Governed Idle Hole
C Hole 1 D Hole 2
E Hole 3 F Hole 4
G Hole 5 H Hole 6
6 mm Governor Lever and Hole Position/RPM Chart
High Idle RPM
Gov. Lever
Hole No.
Governor
Spring Color
Code
3801-4000 5 Clear
3601-3800 4 Clear
3451-3600 3 Clear
3301-3450 2 Clear
3101-3300 4 Purple
2951-3100 3 Purple
2800-2950 2 Purple
3750* 3 Clear
3150* 3 Purple
*5% Regulation (others 10%)
Control Bracket Components (Mechanical
Governor)
E
F
D
C
B
A
A Choke Linkage B Control Bracket
C Spring D Governor Lever
E Nut F Throttle Linkage
Install External Governor Controls (Mechanical
Governor)
1. Install governor lever onto governor cross shaft.
2. Make sure throttle linkage is connected to governor
lever and throttle lever on carburetor.
3. Move governor lever toward carburetor as far as it
will go (wide-open throttle) and hold in position.
4. Insert a nail into hole on cross shaft and rotate shaft
counterclockwise as far as it will turn, then torque
nut to 6.8 N·m (60 in. lb.).
Install Throttle & Choke Controls (Mechanical
Governor)
1. Connect choke linkage to carburetor and choke
actuator lever.
2. Mount main control bracket, and air cleaner support
bracket (if used) to cylinder heads using four screws.
Torque screws to 10.7 N·m (95 in. lb.) into new
holes, or 7.3 N·m (65 in. lb.) into used holes.
3. Connect governor spring from main control bracket
to appropriate hole in governor lever as indicated in
applicable chart. Note that hole positions are
counted from pivot point of governor lever.
Reassembly
84 24 690 30 Rev. GKohlerEngines.com
Governor Lever Hole Position (8 mm)
A
E
D
C
B
A Governor Lever B Hole 1
C Hole 2 D Hole 3
E Hole 4
8 mm Governor Lever and Hole Position/RPM Chart
High Idle RPM
Gov. Lever
Hole No.
Governor
Spring Color
Code
3900-4000 4 Red
3825 3 Orange
3750-3800 3 Purple
3600-3700 3 Black
3500-3550 3 Red
3400-3450 2 Purple
3300-3350 2 Blue
3200-3250 1 Orange
3150 3 Black
3100 2 Clear
3000 1 Red
2900 1 Clear
3744* 2 Orange
3120* 1 Clear
*5% Regulation (others 10%)
Install Oil Sentry
™
(if equipped)
1. Apply pipe sealant with Tefl on
®
(Loctite
®
PST
®
592™
Thread Sealant or equivalent) to threads of Oil
Sentry
™
switch and install it into breather cover.
Torque to 4.5 N·m (40 in. lb.).
2. Connect wire lead (green) to Oil Sentry
™
terminal.
Install Control Panel (if equipped)
1. Install panel to blower housing.
2. Connect throttle control cable or shaft.
3. Connect choke control cable to control bracket.
4. Connect Oil Sentry
™
indicator light wires.
Reassembly
8524 690 30 Rev. G KohlerEngines.com
Install Valve Covers
Torque Sequence
1
2
3
4
NOTE: Do not scrape old RTV sealant (if used) off
sealing surface of cylinder head as this could
cause damage and result in leaks. Use of gasket
remover solvent (paint remover) is
recommended.
Three valve cover designs have been used. First type
used a gasket and RTV sealant between cover and
sealing surface of cylinder head. Second type had a
black O-ring installed in a groove on underside of cover
and may have metal spacers in bolt holes. Latest design
uses a yellow or brown O-ring, with bolt hole spacers
molded in place. Tightening torque diff ers between
gasket and O-ring style covers. Kits are available for
converting to latest O-ring type covers. Diff erences are
pointed out in following installation steps.
1. If using gasket or sealant type cover, prepare sealing
surfaces of cylinder head and cover, refer to Tools
and Aids for approved sealants. Always use fresh
sealant. Using outdated sealant could result in
leakage. With O-ring type covers, make sure sealing
surfaces are clean.
2. Make sure there are no nicks or burrs on sealing
surfaces.
3. For covers requiring RTV sealant, apply a 1.5 mm
(1/16 in.) bead to sealing surface of both cylinder
heads, install a new cover gasket on each, then
apply a second bead of sealant on top surface of
gaskets. For O-ring type covers, install a new O-ring
in groove of each cover. Do not use gaskets or RTV
sealant.
4. Locate cover with oil fi ll neck on same side as
removed and install lifting strap in original position.
With O-ring type covers, position cover on cylinder
head. If loose spacers were used, insert a spacer in
each screw hole. On both types, install four screws
in each cover and fi nger tighten.
5. Torque valve cover fasteners to proper specifi cation
using sequence shown.
Torque Specifi cations-Covers
Gasket/RTV 3.4 N·m (30 in. lb.)
Black O-ring
w/shoulder screws
w/screws and spacers
5.6 N·m (50 in. lb.)
9.9 N·m (88 in. lb.)
Yellow or Brown O-ring
w/integral spacers 9.0 N·m (80 in. lb.)
Install Air Cleaner Assembly
NOTE: Route fuel line in contour to avoid restriction.
1. Attach rubber breather hose to breather cover.
Connect fuel inlet line to carburetor and secure with
a clamp.
2. Position a new gasket and air cleaner base while
carefully pulling loose end of rubber breather hose
through base until properly seated (collars sealed
against each side of base).
3. Secure air cleaner base and bracket using screws.
Position bracket with hole toward breather hose. Be
careful not to drop screws into carburetor. If a rear
air cleaner bracket is used, install two M5 screws
through rear of base. Torque three M6 screws to
6.2-7.3 N·m (55-65 in. lb.) and two rear M5 mounting
screws (when applicable) to 4.0 N·m (35 in. lb.).
4. Install breather hose in hole of bracket.
5. Install air cleaner components, refer to Air Cleaner/
Intake.
Install Muffl er
1. Install port liners (if equipped). Install muffl er and
attaching hardware to muffl er bracket. Torque
screws to 9.9 N·m (88 in. lb.).
2. Install nuts to exhaust studs. Torque nuts to
24.4 N·m (216 in. lb.).
Install Oil Cooler (if equipped)
Oil cooler can now be installed to engine. Two diff erent
styles are used.
1. Depending on style used, reverse removal
procedure from Disassembly.
2. Secure cooler or adapter to oil pan with oil fi lter
nipple. Torque oil fi lter nipple to 27 N·m (20 ft. lb.).
Reassembly
86 24 690 30 Rev. GKohlerEngines.com
Install Oil Filter and Fill Crankcase with Oil
NOTE: Make sure both oil drain plugs are installed and
torqued to specifi cations to prevent oil leakage.
1. Install oil drain plug(s). Torque plug(s) to 13.6 N·m
(10 ft. lb.). If oil drain valve is used, make sure valve
body is closed and cap is on.
2. Place new fi lter in shallow pan with open end up. Fill
with new oil until oil reaches bottom of threads. Allow
2 minutes for oil to be absorbed by fi lter material.
3. Apply a thin fi lm of clean oil to rubber gasket on oil
fi lter.
4. Refer to instructions on oil fi lter for proper
installation.
5. Fill crankcase with new oil. Level should be at top of
indicator on dipstick.
6. Reinstall oil fi ll cap/dipstick and tighten securely.
Connect Spark Plug Leads
Connect leads to spark plugs.
Prepare Engine for Operation
Engine is now completely reassembled. Before starting
or operating engine, be sure to follow these steps.
1. Make sure all hardware is tightened securely.
2. Make sure oil drain plugs, Oil Sentry
™
pressure
switch, and a new oil fi lter are installed.
3. Adjust carburetor, idle fuel needle, or idle speed
adjusting screw as necessary.
Testing Engine
It is recommended engine be operated on a test stand or
bench prior to installation in piece of equipment.
1. Set engine up on a test stand. Install an oil pressure
gauge. Start engine and check to be certain oil
pressure (20 psi or more) is present. Run engine at
idle for 2-3 minutes, then 5-6 minutes more between
idle and midrange. Adjust carburetor mixture settings
as necessary (as available).
2. Adjust idle speed screw and high-speed stop as
necessary. Make sure maximum engine speed does
not exceed 3750 RPM (no load).
Reassembly
8724 690 30 Rev. G KohlerEngines.com
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