Kohler SH255

Kohler SH255The Kohler SH255 is a 196 cc (12.0 cu·in) single-cylinder air-cooled four-stroke internal combustion gasoline engine from SH/3000/Courage series, manufactured by Kohler Co., for general-purpose applications.

The Kohler SH255 engine has an OHV (overhead valve) design, aluminum block with cast iron cylinder liners. This engine is equipped with one-barrel carburetor with fixed main jet, dependable magneto breakerless ignition system and mechanical governor.

Cylinder bore and piston stroke are 68.0 mm (2.7 in) and 54.0 mm (2.1 in), respectively. Compression ratio rating is 8.5:1. The SH255 engine produced 5.7 PS (4.2 KW; 5.5 HP) at 3,600 rpm of horsepower and 13.6 Nm (1.4 kg·m; 10.0 ft·lb) at 3,000 rpm of torque.

The breakdown of the engine code is as follows:

  • SH – SH series
  • 2 – Slanted cylinder
  • 55 – Output power 5.5 HP

General information

Engine Specifications
ModelKohler SH255
Type4-stroke, OHV, single cylinder
Displacement196 cm 3 (12.0 cu-in)
Max. horsepower5.7 PS (4.2 KW; 5.5 HP) at 3,600 rpm
Max. torque (crank PTO)13.6 Nm (1.4 kg·m; 10.0 ft·lb) at 3,000 rpm
Fuel systemOne-barrel carburetor with fixed main jet
Cooling systemForced-air
Ignition systemDependable magneto breakerless
Lubricating systemSplash type
Starting systemRecoil/12V electric (optional) starter
Fuel usedUnleaded gasoline (octane number 86 or higher)
Fuel tank capacity3.3 liters (3.5 US.qts, 2.9 Imp. qts)
Dimensions (L x W x H)253 x 369 x 371 mm (9.9 x 14.5 x 14.6 in)
Weight16.0 kg (35.3 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio:8.5:1
Bore x Stroke68.0 X 54.0 mm (2.7 x 2.1 in)
Sleeve internal diameter68.027-68.035 mm (2.6782-2.6785 in)
Piston skirt outer diameter67.975-67.985 mm (2.6762-2.6766 in)
Number of piston rings (compression / oil):2 / 1
Ring side clearanceTop0.040 mm (0.0016 in)
Second0.040 mm (0.0016 in)
Ring end gapTop0.325-0.400 mm (0.0130-0.0160 in)
Second0.325-0.400 mm (0.0130-0.0160 in)
Connecting rod small end ID18.010-18.015 mm (0.7090-0.7092 in)
Connecting rod big end ID30.021-30.026 mm (1.1819-1.1821 in)
Piston pin outer diameter17.992-17.995 mm (0.7083-0.7084 in)
Main bearing journal outer diameter:24.975-24.989 mm (0.9833-0.9838 in)
Connecting rod journal outer diameter:29.975-29.985 mm (1.1801-1.1805 in)
Cylinder Head
Valve Arrangement:OHV
Valve head diameter:INTAKE25.000 mm (0.9842 in)
EXHAUST24.000 mm (0.9449 in)
Stem outer diameter (standard):INTAKE5.500 mm (0.2165 in)
EXHAUST5.500 mm (0.2165 in)
Valve length (standard):INTAKE64.000 mm (2.5197 in)
EXHAUST62.000 mm (2.4409 in)

Tightening torque specs

Tightening torque specs
Cylinder head (torque in 2 increments) Step 1: 12.0 Nm (1.2 kgf·m; 8.9 ft·lb)
Step 2: 24.0 Nm (2.4 kgf·m; 17.7 ft·lb)
Connecting rod12.0 Nm (1.2 kgf·m; 8.9 ft·lb)
Flywheel74.0 Nm (7.5 kgf·m; 54.6 ft·lb)
Oil drain plug17.0 Nm; (1.73 kg·m; 12.5 ft·lb)
Spark plug27.0 Nm (2.8 kgf·m; 19.9 ft·lb)

Service Information

Idle speed2,000 ± 150 rpm
Valve clearance
Intake valve clearance0.100 mm (0.0040 in)
Exhaust valve clearance0.150 mm (0.0060 in)
Oil system
Oil typeAPI SJ or higher
Recommended oilSAE 10W-30
Oil capacity0.6 L (0.63 US. qt, 0.53 Imp. qt.)
Ignition system
Spark plugChampion: RC12YC
Spark plug gap0.76 mm (0.030 in)
Ignition module air gap0.254 mm (0.0100 in)
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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