The 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 model | Command PRO CH255 |
| Engine type | 4-stroke, OHV, single-cylinder |
| Displacement | 177 cm 3 (10.8 cu-in) |
| Max. horsepower | 5.5 PS (4.0 KW; 5.5 HP) at 3,600 rpm |
| Max. torque | 8.3 Nm (0.85 kg·m; 6.13 ft·lb) at 2,800 rpm |
| Cooling system | Forced air |
| Air cleaner | Quad-Clean heavyduty cyclonic air cleaner |
| Lubricating system | Splash type lubrication |
| Ignition system | Dependable magneto breakerless ignition |
| Fuel system | One-barrel carburetor with fixed main jet |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Fuel tank capacity | 3.0 liters (3.1 US.qts, 2.6 Imp. qts) |
| Starting system | Recoil starter |
| Governor | Mechanical centrifugal governor |
| PTO shaft rotation | Counterclockwise (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 weight | 15.0 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 |
| Valves: | 2 |
| 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 rod | 12.5 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) |
| Flywheel | 74.0 Nm (7.5 kgf·m; 54.6 lb·ft) |
| Spark plug | 27.0 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 gap | 0.254 mm (0.010 in) |
References
1. Kohler Command PRO CH245-CH440 service manual. Kohler Co. 2021.
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