Kohler CH255

Kohler CH255The Kohler CH255 is a 177 cc (10.8 cu·in) natural aspirated single-cylinder four-stroke air-cooled internal combustion small gasoline engine from the Command PRO series with a horizontal shaft, manufactured by Kohler Co for general-purpose applications, such as concrete trowel, concrete screed, log splitter, go-kart, edger, air compressor, tiller, pump, pressure washer and etc.

The cylinder bore and the piston stroke are 68.0 mm (2.70 in) and 49.0 mm (1.90 in), respectively. Compression ratio rating is 8.5:1.

The Kohler CH255 engine produces 5.5 PS (4.0 KW; 5.5 HP) at 3,600 rpm of maximum power and 8.3 Nm (0.85 kg·m; 6.13 ft·lb) at 2,800 rpm of maximum torque.

The Kohler CH255 features:

  • OHV design
  • Aluminum cylinder block
  • Cast iron cylinder liners
  • Swirl-induction combustion chamber
  • Dependable magneto breakerless ignition
  • One-barrel carburetor with fixed main jet
  • Dual ball bearings
  • Steel-forged-andhardened crankshaft
  • Mechanical centrifugal governor
  • Splash type lubrication system
  • Forced air cooling system
  • Recoil starter (12-volt starter available as an option)

General information

Engine Specifications
Engine modelCommand PRO CH255
Engine type4-stroke, OHV, single-cylinder
Displacement177 cm 3 (10.8 cu-in)
Max. horsepower5.5 PS (4.0 KW; 5.5 HP) at 3,600 rpm
Max. torque8.3 Nm (0.85 kg·m; 6.13 ft·lb) at 2,800 rpm
Cooling systemForced air
Air cleanerQuad-Clean heavyduty cyclonic air cleaner
Lubricating systemSplash type lubrication
Ignition systemDependable magneto breakerless ignition
Fuel systemOne-barrel carburetor with fixed main jet
Fuel usedUnleaded gasoline (octane number 86 or higher)
Fuel tank capacity3.0 liters (3.1 US.qts, 2.6 Imp. qts)
Starting systemRecoil starter
GovernorMechanical centrifugal governor
PTO shaft rotationCounterclockwise (from PTO shaft side)
Dimensions (L x W X H)296 x 354 x 318 mm (11.6 x 13.9 x 12.5 in)
Dry weight15.0 kg (33.2 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio:8.5:1
Cylinder bore:68.0 mm (2.70 in)
Piston stroke:49.0 mm (1.90 in)
Cylinder internal diameter (standard):68.027-68.035 mm (2.6280-2.6785 in)
Number of piston rings (compression / oil):2/1
Piston pin diameter:17.992-17.995 mm (0.7083-0.7084 in)
Thrust face outer diameter (standard):67.975-67.985 mm (2.6762-2.6766 in)
Connecting rod big end diameter (standard):30.021-30.026 mm (1.1819-1.1823 in)
Ring-to-groove side clearance (Top):0.040-0.150 mm (0.0020-0.0060 in)
Ring-to-groove side clearance (Second):0.040-0.150 mm (0.0020-0.0060 in)
Ring-to-groove side clearance (Oil):0.050-0.190 mm (0.0019-0.0075 in)
Ring end gap (Top):0.325-0.400 mm (0.0130-0.0160 in)
Ring end gap (Second):0.325-0.400 mm (0.0130-0.0160 in)
Crankshaft main journal diameter:24.975-24.989 mm (0.9833-0.9838 in)
Crankpin journal diameter:24.975-24.989 mm (0.9833-0.9838 in)
Cylinder head
Valve arrangement:OHV
Valve head diameter (INTAKE):24.875-25.125 mm (0.9793-0.9892 in)
Valve head diameter (EXHAUST):23.800-24.200 mm (0.9370-0.9527 in)
Valve seat angle (INTAKE):89.5°-90.5°
Valve seat angle (EXHAUST):89.5°-90.5°
Valve seat angle (INTAKE):89.5°-90.5°
Valve seat angle (EXHAUST):89.5°-90.5°
Valve steam diameter (INTAKE):5.474 mm (0.2155 in)
Valve steam diameter (EXHAUST):5.464 mm (0.2151 in)
Cam lobe profile (INTAKE):27.608 mm (1.0870 in)
Cam lobe profile (EXHAUST):27.770 mm (1.0930 in)

Tightening torque specs

Tightening torque specs
Connecting rod12.5 Nm (1.3 kgf·m; 9.2 lb·ft)
Cylinder head (torque in 2 increments) Step 1: 12.0 Nm (1.2 kgf·m; 8.9 lb·ft)
Step 2: 24.0 Nm (2.4 kgf·m; 17.7 lb·ft)
Flywheel74.0 Nm (7.5 kgf·m; 54.6 lb·ft)
Spark plug27.0 Nm (2.75 kg·m; 20.0 ft·lb)

Service Data

Valve lash
Intake/Exhaust:0.0762-0.1270 mm (0.0030-0.0050 in)
Oil system
Lubrication system:Splash type
Oil type:API SJ or higher
Recommended oil:SAE 10W-30
Oil capacity:0.6 liters (0.63 US.qts, 0.53 Imp. qts)
Fuel system
Type:Carburetor with fixed main jet
Fuel filter:In-line fuel filter
Ignition system
Type:Dependable magneto breakerless ignition
Spark plug:Kohler 1413214-S
Spark plug gap:0.76 mm (0.030 in)
Module air gap0.254 mm (0.010 in)


1. Kohler Command PRO CH245-CH440 service manual. Kohler Co. 2021.

Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

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