Kohler COMMAND CH18 User manual

SERVICE MANUAL
HORIZONTAL CRANKSHAFT
COMMAND CH18-750

Contents
Section 1. Safety and General Information ............................................................................
Section 2. Special Tools ..........................................................................................................
Section 3. Troubleshooting .....................................................................................................
Section 4. Air Cleaner and Air Intake System ........................................................................
Section 5. Fuel System and Governor....................................................................................
Section 5A. LPG Fuel Systems ...............................................................................................
Section 5B. Electronic Fuel Injection (EFI) Fuel System ......................................................
Section 6. Lubrication System ................................................................................................
Section 7. Retractable Starter .................................................................................................
Section 8. Electrical System and Components .....................................................................
Section 9. Disassembly ...........................................................................................................
Section 10. Inspection and Reconditioning ...........................................................................
Section 11. Reassembly...........................................................................................................
Section 12. Clutch ....................................................................................................................
2
1
8
9
10
11
12
4
5
6
7
3
5A
5B

1.1
Section 1
Safety and General Information
1
Section 1
Safety and General Information
Safety Precautions
To ensure safe operation please read the following statements and understand their meaning. Also
refer to your equipment manufacturer's manual for other important safety information. This manual
contains safety precautions which are explained below. Please read carefully.
WARNING
Warning is used to indicate the presence of a hazard that can cause severe personal injury, death,
or substantial property damage if the warning is ignored.
CAUTION
Caution is used to indicate the presence of a hazard that will or can cause minor personal injury or
property damage if the caution is ignored.
NOTE
Note is used to notify people of installation, operation, or maintenance information that is important
but not hazard-related.
For Your Safety!
These precautions should be followed at all times. Failure to follow these precautions could result in injury to yourself
and others.
Rotating Parts can cause severe
injury.
Stay away while engine is in
operation.
WARNING
Rotating Parts!
Keep hands, feet, hair, and clothing away
from all moving parts to prevent injury.
Never operate the engine with covers,
shrouds, or guards removed.
Hot Parts can cause severe burns.
Do not touch engine while operating
or just after stopping.
WARNING
HotParts!
Engine components can get extremely
hot from operation. To prevent severe
burns, do not touch these areas while the
engine is running - or immediately after it
is turned off. Never operate the engine
with heat shields or guards removed.
Accidental Starts can cause severe
injury or death.
Disconnect and ground spark plug
leads before servicing.
WARNING
Accidental Starts!
Disabling engine. Accidental starting
can cause severe injury or death.
Before working on the engine or
equipment, disable the engine as follows:
1) Disconnect the spark plug lead(s). 2)
Disconnect negative (-) battery cable
from battery.

1.2
Section 1
Safety and General Information
Carbon Monoxide can cause severe
nausea, fainting or death.
Avoid inhaling exhaust fumes, and
never run the engine in a closed
building or confined area.
WARNING WARNING
Electrical Shock can cause injury.
Do not touch wires while engine is
running.
CAUTION
Uncoiling Spring can cause severe
injury.
Wear safety goggles or face
protection when servicing
retractable starter.
WARNING
Explosive Gas can cause fires and
severe acid burns.
Charge battery only in a well
ventilated area. Keep sources of
ignition away.
Lethal Exhaust Gases!
Engine exhaust gases contain poisonous
carbon monoxide. Carbon monoxide is
odorless, colorless, and can cause death if
inhaled. Avoid inhaling exhaust fumes,
and never run the engine in a closed
building or confined area.
Spring Under Tension!
Retractable starters contain a powerful,
recoil spring that is under tension.
Always wear safety goggles when
servicing retractable starters and
carefully follow instructions in the
"Retractable Starter" Section 7 for
relieving spring tension.
ExplosiveGas!
Batteries produce explosive hydrogen gas
while being charged. To prevent a fire or
explosion, charge batteries only in well
ventilated areas. Keep sparks, open
flames, and other sources of ignition
away from the battery at all times. Keep
batteries out of the reach of children.
Remove all jewelry when servicing
batteries.
Before disconnecting the negative (-)
ground cable, make sure all switches are
OFF. If ON, a spark will occur at the
ground cable terminal which could cause
an explosion if hydrogen gas or gasoline
vapors are present.
Explosive Fuel can cause fires and
severe burns.
WARNING
Explosive Fuel!
Gasoline is extremely flammable and its
vapors can explode if ignited. Store
gasoline only in approved containers, in
well ventilated, unoccupied buildings,
away from sparks or flames. Do not fill
the fuel tank while the engine is hot or
running, since spilled fuel could ignite if
it comes in contact with hot parts or
sparks from ignition. Do not start the
engine near spilled fuel. Never use
gasoline as a cleaning agent.
Cleaning Solvents can cause severe
injury or death.
Use only in well ventilated areas
away from ignition sources.
WARNING
Flammable Solvents!
Carburetor cleaners and solvents are
extremely flammable. Keep sparks,
flames, and other sources of ignition
away from the area. Follow the cleaner
manufacturer’s warnings and
instructions on its proper and safe use.
Never use gasoline as a cleaning agent.
Electrical Shock!
Never touch electrical wires or
components while the engine is running.
They can be sources of electrical shock.
Do not fill the fuel tank while the
engine is hot or running.

1.3
Section 1
Safety and General Information
1
A. Model No.
Version Code
S = Electric Start
C H 18 S
Engine Identification Numbers
When ordering parts, or in any communication
involving an engine, always give the Model,
Specification and Serial Numbers, including letter
suffixes if there are any.
The engine identification numbers appear on a decal,
or decals, affixed to the engine shrouding. See Figure
1-1. An explanation of these numbers is shown in
Figure 1-2.
Figure 1-1. Engine Identification Decal Location.
Variation of
Basic Engine
B. Spec. No. 62500
Command Engine
Horizontal Crankshaft
Horsepower
17 = 17 HP
18 = 18 HP
20 = 20 HP
22 = 22 HP
23 = 23 HP
25 = 25 HP
26 = 26 HP
Numerical Designation
730
740
745
750
or
Engine Model Code
Code Model
62 CH18
64 CH20
66 CH22 (624 cc)
68 CH25
76 CH22/23 (674 cc)
78 CH26
CH730-0001
CH740-0001
CH745-0001
CH750-0001
CompleteSpecNumber
(IncorporatingModelNo.
withVariationNo. of
Basic Spec.)
or
Figure 1-2. Explanation of Engine Identification Numbers.
C. Serial No.
Year Manufactured Code
Code Year
21 1991
22 1992
23 1993
24 1994
25 1995
26 1996
27 1997
28 1998
29 1999
Factory Code
3305810334
Code Year
30 2000
31 2001
32 2002
33 2003
34 2004
35 2005
36 2006
37 2007
Identification Decal

1.4
Section 1
Safety and General Information
Oil Recommendations
Using the proper type and weight of oil in the
crankcase is extremely important. So is checking oil
daily and changing oil regularly. Failure to use the
correct oil, or using dirty oil, causes premature engine
wear and failure.
Oil Type
Use high-quality detergent oil of API (American
Petroleum Institute) Service Class SG, SH, SJ or higher.
Select the viscosity based on the air temperature at the
time of operation as shown in the following table.
Refer to Section 6 - “Lubrication System” for detailed
procedures on checking the oil, changing the oil and
changing the oil filter.
Fuel Recommendations
WARNING: Explosive Fuel!
Gasoline is extremely flammable and its vapors can explode if
ignited. Before servicing the fuel system, make sure there are no
sparks, open flames or other sources of ignition nearby as these
can ignite gasoline vapors. Disconnect and ground the spark plug
leads to prevent the possibility of sparks from the ignition system.
General Recommendations
Purchase gasoline in small quantities and store in clean,
approved containers. A container with a capacity of 2
gallons or less with a pouring spout is recommended.
Such a container is easier to handle and helps eliminate
spillage during refueling.
Do not use gasoline left over from the previous season,
to minimize gum deposits in your fuel system and to
ensure easy starting.
Do not add oil to the gasoline.
Do not overfill the fuel tank. Leave room for the fuel to
expand.
Fuel Type
For best results, use only clean, fresh, unleaded gasoline
with a pump sticker octane rating of 87 or higher. In
countries using the Research method, it should be 90
octane minimum.
Unleaded gasoline is recommended as it leaves less
combustion chamber deposits and reduces harmful
exhaust emissions. Leaded gasoline is not recommended
and must not be used on EFI engines, or on other models
where exhaust emissions are regulated.
Gasoline/Alcohol blends
Gasohol (up to 10% ethyl alcohol, 90% unleaded gasoline
by volume) is approved as a fuel for Kohler engines.
Other gasoline/alcohol blends are not approved.
Gasoline/Ether blends
Methyl Tertiary Butyl Ether (MTBE) and unleaded
gasoline blends (up to a maximum of 15% MTBE by
volume) are approved as a fuel for Kohler engines. Other
gasoline/ether blends are not approved.
NOTE: Using other than service class SG, SH, SJ or
higher oil or extending oil change intervals
longer than recommended can cause engine
damage.
NOTE: Synthetic oils meeting the listed
classifications may be used with oil changes
performed at the recommended intervals.
However, to allow piston rings to properly
seat, a new or rebuilt engine should be
operated for at least 50 hours using standard
petroleum based oil before switching to
synthetic oil.
A logo or symbol on oil containers identifies the API
service class and SAE viscosity grade. See Figure 1-3.
Figure 1-3. Oil Container Logo.
*
*Use of synthetic oil having 5W-20 or 5W-30 rating is
acceptable, up to 4°C (40°F).
**Synthetic oils will provide better starting in
extreme cold (below -23°C (-10°F).
**

1.5
Section 1
Safety and General Information
1
Periodic Maintenance Instructions
WARNING: Accidental Starts!
Disabling engine. Accidental starting can cause severe injury or death. Before working on the engine or equipment,
disable the engine as follows: 1) Disconnect the spark plug lead(s). 2) Disconnect negative (-) battery cable from battery.
Maintenance Schedule
These required maintenance procedures should be performed at the frequency stated in the table. They should
also be included as part of any seasonal tune-up.
Storage
If the engine will be out of service for two months or
more, use the following storage procedure:
1. Clean the exterior surfaces of the engine. On
Electronic Fuel Injected (EFI) engines, avoid
spraying water at the wiring harness or any of
the electrical components.
2. Change the oil and oil filter while the engine is
still warm from operation. See “Change Oil and
Oil Filter” in Section 6.
3. The fuel system must be completely emptied, or
the gasoline must be treated with a stabilizer to
prevent deterioration. If you choose to use a
stabilizer, follow the manufacturer’s
recommendations, and add the correct amount
for the capacity of the fuel system.
Fill the fuel tank with clean, fresh gasoline. Run
the engine for 2 to 3 minutes to get stabilized fuel
into the rest of the system. Close the fuel shut-off
valve when the unit is being stored or
transported.
To empty the system, run the engine until the
tank and the system are empty.
4. Remove the spark plugs and add one tablespoon
of engine oil into each spark plug hole. Install the
spark plugs, but do not connect the plug leads.
Crank the engine two or three revolutions.
5. On equipment with an EFI engine, disconnect the
battery or use a battery minder to keep the
battery charged during storage.
6. Store the engine in a clean, dry place.
• Replace fuel filter1(EFI engines). Section 5B
Daily or Before
Starting Engine
Maintenance RequiredFrequency
• Fill fuel tank Section 5
• Check oil level. Section 6
• Check air cleaner for dirty1, loose, or damaged parts. Section 4
• Check air intake and cooling areas, clean as necessary1. Section 4
• Service precleaner element1. Section 4
Every 25 Hours
• Replace air cleaner element1. Section 4
• Change oil. (More frequently under severe conditions.) Section 6
• Remove cooling shrouds and clean cooling areas1,3. Section 4
• Check oil cooler fins, clean as necessary (if equipped). Section 6
• Check spark plug condition and gap. Section 8
• Change oil filter. Section 6
• Change fuel filter (carbureted engines). Section 5
Annually or
Every 500 Hours • Have bendix starter drive serviced2. Section 8
• Have solenoid shift starter disassembled and cleaned2. Section 8
Every 100 Hours
Every 200 Hours
Every 1500 Hours
• Have crankshaft splines lubricated2. Section 2
Every 500 Hours
Every 250 Hours • Replace heavy-duty air cleaner element and check inner element1. Section 4
¹Perform these maintenance procedures more frequently under extremely dusty, dirty conditions.
²Only requried for Denso starters. Not necessary on Delco starters. Have a Kohler Engine Service Dealer perform this service.
³Cleanout Kits 25 755 20-S (black) or 25 755 21-S (gold) allow cooling areas to be cleaned without removing shrouds.
Refer to:

1.6
Section 1
Safety and General Information
Figure 1-4. Typical Engine Dimensions CH Series with Standard Flat Air Cleaner.
Dimensions in millimeters.
Inch equivalents shown in [ ].

1.7
Section 1
Safety and General Information
1
Figure 1-5. Typical Engine Dimensions CH EFI Series with Heavy-Duty Air Cleaner.
Dimensions in millimeters.
Inch equivalents shown in [ ].

1.8
Section 1
Safety and General Information
General Specifications¹
Power (@ 3600 RPM, exceeds Society of Automotive Engineers-Small Engine Test Code J1940.)
CH18 ........................................................................................................................................ 13.4 kW (18 HP)
CH20 ........................................................................................................................................ 14.9 kW (20 HP)
CH22 ........................................................................................................................................ 16.4 kW (22 HP)
CH23 ........................................................................................................................................ 17.2 kW (23 HP)
CH25, CH730 .......................................................................................................................... 18.6 kW (25 HP)
CH26 ........................................................................................................................................ 19.4 kW (26 HP)
CH740 ...................................................................................................................................... 20.1 kW (27 HP)
CH745 ...................................................................................................................................... 20.9 kW (28 HP)
CH750 ...................................................................................................................................... 22.3 kW (30 HP)
Peak Torque
CH18 @ 2200 RPM ................................................................................................................. 43.6 N·m (32.2 ft. lb.)
CH20 @ 2400 RPM ................................................................................................................. 44.3 N·m (32.7 ft. lb.)
CH22 @ 2400 RPM ................................................................................................................. 49.1 N·m (36.2 ft. lb.)
CH23 @ 2400 RPM ................................................................................................................. 54.1 N·m (37.9 ft. lb.)
CH25 @ 2200 RPM ................................................................................................................. 54.0 N·m (39.5 ft. lb.)
CH730 @ 2400 RPM ............................................................................................................... 55.4 N·m (40.9 ft. lb.)
CH26 @ 2800 RPM ................................................................................................................. 54.2 N·m (40.0 ft. lb.)
CH740 @ 2400 RPM ............................................................................................................... 57.3 N·m (42.3 ft. lb.)
CH745 @ 2600 RPM ............................................................................................................... 57.9 N·m (42.7 ft. lb.)
CH750 @ 2400 RPM ............................................................................................................... 64.4 N·m (47.5 ft. lb.)
Bore
CH18, CH20, CH22 (624 cc) .................................................................................................. 77 mm (3.03 in.)
CH22/23 (674 cc) .................................................................................................................... 80 mm (3.15 in.)
CH25, CH26, CH730-750 ....................................................................................................... 83 mm (3.27 in.)
Stroke
CH18-745 ................................................................................................................................ 67 mm (2.64 in.)
CH750 ...................................................................................................................................... 69 mm (2.7 in.)
Displacement
CH18, CH20, CH22 (624 cc) .................................................................................................. 624 cc (38 cu. in.)
CH22/23 (674 cc) .................................................................................................................... 674 cc (41 cu. in.)
CH25, CH26, CH730-745 ....................................................................................................... 725 cc (44 cu. in.)
CH750 ...................................................................................................................................... 755 cc (46 cu. in.)
Compression Ratio
CH18, CH20, CH22/23 ........................................................................................................... 8.5:1
CH25, CH26, CH730-745 ....................................................................................................... 9.0:1
CH750 ...................................................................................................................................... 9.4:1
Dry Weight
CH18, CH20, CH22/23 ........................................................................................................... 41 kg (90 lb.)
CH25, CH26, CH730-745 ....................................................................................................... 43 kg (94 lb.)
CH750 ...................................................................................................................................... 48 kg (105 lb.)
Oil Capacity (w/filter) - approximate,
determined by oil filter and oil cooler used ............................................................................. 1.6-1.8 L (1.7-1.9 U.S. qt.)
¹Values are in Metric units. Values in parentheses are English equivalents. Lubricate threads with engine oil
prior to assembly.

1.9
Section 1
Safety and General Information
1
General Specifications¹ cont.
Angle of Operation - Maximum (At Full Oil Level) All Directions ................... 25°
Blower Housing and Sheet Metal
M5 Fasteners Torque ................................................................................................ 6.2 N·m (55 in. lb.) into new holes
4.0 N·m (35 in. lb.) into used holes
M6 Fasteners Torque ................................................................................................ 10.7 N·m (95 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
Rectifier-Regulator Fastener Torque ................................................................... 1.4 N·m (12.6 in. lb.)
Camshaft
End Play (With 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 .................................................................................................................. 20.000/20.025 mm (0.7874/0.7884 in.)
Max. Wear Limit ............................................................................................. 20.038 mm (0.7889 in.)
Camshaft Bearing Surface O.D.
New .................................................................................................................. 19.962/19.975 mm (0.7859/0.7864 in.)
Max. Wear Limit ............................................................................................. 19.959 mm (0.7858 in.)
Carburetor and Intake Manifold
Intake Manifold Mounting Fastener Torque
Torque in Two Stages ..................................................................................... first to 7.4 N·m (66 in. lb.)
finally to 9.9 N·m (88 in. lb.)
Carburetor Mounting Screw Torque M6 ............................................................ 6.2-7.3 N·m (55-65 in. lb.)
Adapter (for Heavy Duty Air Cleaner) Mounting Fastener Torque ................ 7.3 N·m (65 in. lb.)
Connecting Rod
Cap Fastener Torque (torque in increments)
8 mm straight shank ............................................................................................ 22.7 N·m (200 in. lb.)
8 mm step-down .................................................................................................. 14.7 N·m (130 in. lb.)
6 mm straight shank ............................................................................................ 11.3 N·m (100 in. lb.)
Connecting Rod-to-Crankpin Running Clearance
New .................................................................................................................. 0.030/0.055 mm (0.0012/0.0022 in.)
Max. Wear Limit ............................................................................................. 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 .................................................................................................................. 17.015/17.023 mm (0.6699/0.6702 in.)
Max. Wear Limit ............................................................................................. 17.036 mm (0.6707 in.)
¹Values are in Metric units. Values in parentheses are English equivalents. Lubricate threads with engine oil
prior to assembly.

1.10
Section 1
Safety and General Information
Crankcase
Governor Cross Shaft Bore I.D.
6 mm Shaft
New .................................................................................................................. 6.025/6.050 mm (0.2372/0.2382 in.)
Max. Wear Limit ............................................................................................. 6.063 mm (0.2387 in.)
8 mm Shaft
New .................................................................................................................. 8.025/8.075 mm (0.3159/0.3179 in.)
Max. Wear Limit ............................................................................................. 8.088 mm (0.3184 in.)
Breather Cover Fastener Torque .......................................................................... 7.3 N·m (65 in. lb.)
Oil Drain Plug Torque ............................................................................................ 13.6 N·m (10 ft. lb.)
Closure Plate
Closure Plate Fastener Torque .............................................................................. 24.4 N·m (216 in. lb.)
Crankshaft
End Play (Free) ........................................................................................................ 0.070/0.590 mm (0.0028/0.0230 in.)
End Play (With Thrust Bearing Components) ................................................... 0.070/0.270 mm (0.0028/0.0100 in.)
Except CH25 Engines Below Serial No. 2403500008 .......................................... 0.050/0.750 mm (0.0020/0.0295 in.)
Crankshaft Bore (In Crankcase)
New .................................................................................................................. 40.965/41.003 mm (1.6128/1.6143 in.)
Max. Wear Limit ............................................................................................. 41.016 mm (1.6148 in.)
Crankshaft to Sleeve Bearing (Crankcase)
Running Clearance - New ............................................................................ 0.03/0.09 mm (0.0012/0.0035 in.)
Crankshaft 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 ....................................................................................................... 40.913/40.935 mm (1.6107/1.6116 in.)
O.D. - Max. Wear Limit .................................................................................. 40.84 mm (1.608 in.)
Max. Taper ....................................................................................................... 0.022 mm (0.0009 in.)
Max. Out-of-Round ........................................................................................ 0.025 mm (0.0010 in.)
Closure Plate End Main Bearing Journal
O.D. - New ....................................................................................................... 40.913/40.935 mm (1.6107/1.6116 in.)
O.D. - Max. Wear Limit .................................................................................. 40.84 mm (1.608 in.)
Max. Taper ....................................................................................................... 0.022 mm (0.0009 in.)
Max. Out-of-Round ........................................................................................ 0.025 mm (0.0010 in.)
Connecting Rod Journal
O.D. - New ....................................................................................................... 35.955/35.973 mm (1.4156/1.4163 in.)
O.D. - Max. Wear Limit .................................................................................. 35.94 mm (1.415 in.)
Max. Taper ....................................................................................................... 0.018 mm (0.0007 in.)
Max. Out-of-Round ........................................................................................ 0.025 mm (0.0010 in.)

1.11
Section 1
Safety and General Information
1
Crankshaftcont.
Crankshaft T.I.R.
PTO End, Crank in Engine ............................................................................. 0.279 mm (0.0110 in.)
Entire Crank, in V-Blocks .............................................................................. 0.10 mm (0.0039 in.)
Cylinder Bore
Cylinder Bore I.D.
New - CH18, CH20, CH22 (624 cc) ............................................................... 77.000/77.025 mm (3.0315/3.0325 in.)
New - CH22/23 (674 cc) ................................................................................. 80.000/80.025 mm (3.1496/3.1506 in.)
New - CH25, CH26, CH730-750 ................................................................... 82.988/83.013 mm (3.2672/3.2682 in.)
Max. Wear Limit - CH18, CH20, CH22 (624 cc) .......................................... 77.063 mm (3.0340 in.)
Max. Wear Limit - CH22/23 (674 cc) ............................................................ 80.065 mm (3.1522 in.)
Max. Wear Limit - CH25, CH26, CH730-750 .............................................. 83.051 mm (3.2697 in.)
Max. Out-of-Round ........................................................................................ 0.12 mm (0.0047 in.)
Max. Taper ....................................................................................................... 0.05 mm (0.0020 in.)
Cylinder Head
Cylinder Head Fastener Torque
Hex Flange Nut - Torque in Two Stages ...................................................... first to 16.9 N·m (150 in. lb.)
finally to 33.9 N·m (300 in. lb.)
Head Bolt - Torque in Two Stages ................................................................ first to 22.6 N·m (200 in. lb.)
finally to 41.8 N·m (370 in. lb.)
Max. Out-of-Flatness .............................................................................................. 0.076 mm (0.003 in.)
Rocker Arm Screw Torque .................................................................................... 11.3 N·m (100 in. lb.)
Fan/Flywheel
Fan Fastener Torque ............................................................................................... 9.9 N·m (88 in. lb.)
Flywheel Retaining Screw Torque ....................................................................... 66.4 N·m (49 ft. lb.)
Governor
Governor Cross Shaft-to-Crankcase Running Clearance
6 mm Shaft............................................................................................................. 0.013/0.075 mm (0.0005/0.0030 in.)
8 mm Shaft............................................................................................................. 0.025/0.126 mm (0.0009/0.0049 in.)
Governor Cross Shaft O.D.
6 mm Shaft
New .................................................................................................................. 5.975/6.012 mm (0.2352/0.2367 in.)
Max. Wear Limit ............................................................................................. 5.962 mm (0.2347 in.)
8 mm Shaft
New .................................................................................................................. 7.949/8.000 mm (0.3129/0.3149 in.)
Max. Wear Limit ............................................................................................. 7.936 mm (0.3124 in.)
Governor Gear Shaft-to-Governor Gear Running Clearance ......................... 0.015/0.140 mm (0.0006/0.0055 in.)
Governor Gear Shaft O.D.
New .................................................................................................................. 5.990/6.000 mm (0.2358/0.2362 in.)
Max. Wear Limit ............................................................................................. 5.977 mm (0.2353 in.)
Governor Lever Nut Torque ................................................................................. 6.8 N·m (60 in. lb.)

1.12
Section 1
Safety and General Information
Ignition
Spark Plug Type (Champion®or Equivalent) ..................................................... RC12YC, XC12YC, or Platinum 3071
Spark Plug Gap ....................................................................................................... 0.76 mm (0.030 in.)
Spark Plug Torque .................................................................................................. 24.4-29.8 N·m (18-22 ft. lb.)
Ignition Module Air Gap ....................................................................................... 0.28/0.33 mm (0.011/0.013 in.)
Ignition Module Fastener Torque ......................................................................... 4.0-6.2 N·m (35-55 in. lb.)
Speed Sensor Air Gap (EFI engines) ..................................................................... 1.50 ± 0.25 mm (0.059 ± 0.010 in.)
Muffler
Muffler Retaining Nut Torque .............................................................................. 24.4 N·m (216 in. lb.)
Oil Filter
Oil Filter Torque ...................................................................................................... 3/4-1 turn after gasket contact
Oil Cooler
Oil Cooler/Adapter Nipple Torque ...................................................................... 27 N·m (20 ft. lb.)
Piston, Piston Rings, and Piston Pin
Piston-to-Piston Pin Running Clearance ............................................................ 0.006/0.017 mm (0.0002/0.0007 in.)
Piston Pin Bore I.D.
New .................................................................................................................. 17.006/17.012 mm (0.6695/0.6698 in.)
Max. Wear Limit ............................................................................................. 17.025 mm (0.6703 in.)
Piston Pin O.D.
New .................................................................................................................. 16.995/17.000 mm (0.6691/0.6693 in.)
Max. Wear Limit ............................................................................................. 16.994 mm (0.6691 in.)
Top Compression Ring-to-Groove Side Clearance
CH18, CH20, CH22 (624 cc) ........................................................................... 0.040/0.080 mm (0.0016/0.0031 in.)
CH22/23 (674 cc) ............................................................................................. 0.030/0.076 mm (0.0012/0.0030 in.)
CH25, CH26, CH730-750 ............................................................................... 0.025/0.048 mm (0.0010/0.0019 in.)
Middle Compression Ring-to-Groove Side Clearance
CH18, CH20, CH22 (624 cc) ........................................................................... 0.040/0.080 mm (0.0016/0.0031 in.)
CH22/23 (674 cc) ............................................................................................. 0.030/0.076 mm (0.0012/0.0030 in.)
CH25, CH26, CH730-750 ............................................................................... 0.015/0.037 mm (0.0006/0.0015 in.)
Oil Control Ring-to-Groove Side Clearance
CH18, CH20, CH22 (624 cc) ........................................................................... 0.060/0.202 mm (0.0024/0.0080 in.)
CH22/23 (674 cc) ............................................................................................. 0.046/0.196 mm (0.0018/0.0077 in.)
CH25, CH26, CH730-750 ............................................................................... 0.026/0.176 mm (0.0010/0.0070 in.)

1.13
Section 1
Safety and General Information
1
²Measure 6 mm (0.236 in.) above the bottom of the piston skirt at right angles to the piston pin.
Piston, Piston Rings, and Piston Pin cont.
Top and Center Compression Ring End Gap
New Bore - CH18, CH20, CH22 (624 cc) ...................................................... 0.25/0.45 mm (0.0098/0.0177 in.)
New Bore - CH22/23 (674 cc) ........................................................................ 0.18/0.46 mm (0.0071/0.0181 in.)
New Bore - CH25, CH26, CH730-745 .......................................................... 0.25/0.56 mm (0.0100/0.0224 in.)
Used Bore (Max.) - CH18, CH20, CH22 (624 cc) .......................................... 0.77 mm (0.030 in.)
Used Bore (Max.) - CH22/23 (674 cc) ............................................................ 0.80 mm (0.0315 in.)
Used Bore (Max.) - CH25, CH26, CH730-750 .............................................. 0.94 mm (0.037 in.)
Piston Thrust Face O.D.²
New - CH18, CH20, CH22 (624 cc) ............................................................... 76.967/76.985 mm (3.0302/3.0309 in.)
New - CH22/23 (674 cc) ................................................................................. 79.963/79.979 mm (3.1481/3.1488 in.)
New - CH25, CH26, CH730-750 ................................................................... 82.986 mm (3.2671 in.)
Max. Wear Limit - CH18, CH20, CH22 (624 cc) .......................................... 76.840 mm (3.0252 in.)
Max. Wear Limit - CH22 (674 cc) ................................................................. 79.831 mm (3.1430 in.)
Max. Wear Limit - CH25, CH26, CH730-750 .............................................. 82.841 mm (3.2614 in.)
Piston Thrust Face-to-Cylinder Bore² Running Clearance
New - CH18, CH20, CH22 (624 cc) ............................................................... 0.014/0.057 mm (0.0005/0.0022 in.)
New - CH22/23 (674 cc) ................................................................................. 0.021/0.062 mm (0.0008/0.0024 in.)
New - CH25, CH26, CH730-750 ................................................................... 0.001/0.045 mm (0.039/0.0018 in.)
Speed Control Bracket
Fastener Torque ....................................................................................................... 10.7 N·m (95 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
Starter Assembly
Thru Bolt Torque
UTE/Johnson Electric, Eaton (Inertia Drive) ............................................... 4.5-5.7 N·m (40-50 in. lb.)
Nippondenso (Solenoid Shift) ...................................................................... 4.5-7.5 N·m (40-84 in. lb.)
Delco-Remy (Solenoid Shift) ......................................................................... 5.6-9.0 N·m (49-79 in. lb.)
Mounting Screw Torque (All) ............................................................................... 15.3 N·m (135 in. lb.)
Brush Holder Mounting Screw Torque
Delco-Remy Starter ........................................................................................ 2.5-3.3 N·m (22-29 in. lb.)
Solenoid (Starter)
Mounting Hardware Torque
Nippondenso Starter ..................................................................................... 6.0-9.0 N·m (53-79 in. lb.)
Delco-Remy Starter ........................................................................................ 4.0-6.0 N·m (35-53 in. lb.)
Nut, Positive (+) Brush Lead Torque
Nippondenso Starter ..................................................................................... 8.0-12.0 N·m (71-106 in. lb.)
Delco-Remy Starter ........................................................................................ 8.0-11.0 N·m (71-97 in. lb.)
Stator
Mounting Screw Torque ........................................................................................ 6.2 N·m (55 in. lb.)

1.14
Section 1
Safety and General Information
Valve Cover
Valve Cover Fastener Torque
Gasket Style Cover ................................................................................................. 3.4 N·m (30 in. lb.)
Black O-Ring Style Cover
w/Shoulder Screws ........................................................................................ 5.6 N·m (50 in. lb.)
w/Flange Screws and Spacers ...................................................................... 9.9 N·m (88 in. lb.)
Yellow or Brown O-Ring Style Cover w/Integral Metal Spacers .................... 6.2 N·m (55 in. lb.)
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 .................................................................................................................. 7.038/7.058 mm (0.2771/0.2779 in.)
Max. Wear Limit ............................................................................................. 7.134 mm (0.2809 in.)
Exhaust Valve Guide I.D.
New .................................................................................................................. 7.038/7.058 mm (0.2771/0.2779 in.)
Max. Wear Limit ............................................................................................. 7.159 mm (0.2819 in.)
Valve Guide Reamer Size
Standard .......................................................................................................... 7.048 mm (0.2775 in.)
0.25 mm O.S. .................................................................................................... 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°

1.15
Section 1
Safety and General Information
1
Tightening Torque: N·m (in. lb.) + or - 10%
Property Class Noncritical
Fasteners
IntoAluminum
Size
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.) + or - 10%
Property Class Noncritical
Fasteners
IntoAluminum
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 (55) 131.5 (97) 184.4 (136) 219.7 (162) 94.9 (70)
5.8 8.8 10.9 12.9
4.8 5.8 10.9 12.9
4.8
8.8
General Torque Values
Metric Fastener Torque Recommendations for Standard Applications

1.16
Section 1
Safety and General Information
English Fastener Torque Recommendations for StandardApplications
Grade 2 or 5
Fasteners Into
Aluminum
Size
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) --------- --------- ---------
Size
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) 142.4 (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) ---------
5/8-11 149.2 (110) 244.1 (180) 352.6 (260) ---------
5/8-18 189.8 (140) 311.9 (230) 447.5 (330) ---------
3/4-10 199.3 (150) 332.2 (245) 474.6 (350) ---------
3/4-16 271.2 (200) 440.7 (325) 637.3 (470) ---------
Tightening Torque: N·m (ft. lb.) + or - 20%
Tightening Torque: N·m (in. lb.) + or - 20%
Grade 2 Grade 5 Grade 8
Bolts, Screws, Nuts and Fasteners
Assembled Into Cast Iron or Steel
N·m = in. lb. x 0.113
N·m = ft. lb. x 1.356
in. lb. = N·m x 8.85
ft. lb. = N·m x 0.737
Torque
Conversions

2.1
Section 2
Tools & Aids
2
Section 2
Tools & Aids
Certain quality tools are designed to help you perform specific disassembly, repair, and reassembly procedures.
By using tools designed for the job, 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 the list of tools and their source.
Separate Tool Suppliers:
Kohler Tools
Contact your source
of supply.
SE Tools
415 Howard St.
Lapeer, MI 48446
Phone [phone]
Toll Free 800-664-2981
Fax [phone]
Design Technology Inc.
768 Burr Oak Drive
Westmont, IL 60559
Phone [phone]
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Tools & Aids
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