Kohler M8

Kohler M8The Kohler M8 is a 305 cc (18.64 cu·in) single-cylinder air-cooled four-stroke internal combustion gasoline engine from the Magnum-series, manufactured by Kohler Co.

The Kohler M8 engine has an L-head (side valve) design and a horizontal PTO shaft. This engine is equipped with the Kohler-build side-draft carburetor with an adjustable jet and an electronic magneto ignition system. The M8 engine used a high-density paper air cleaner.

The cylinder bore is 74.7 mm (2.94 in) and the piston stroke is 69.85 mm (2.75 in). The compression ratio rating is 6.8:1.

The Kohler M8 engine produced 8.2 PS (6.0 KW; 8.0 HP) at 3,600 rpm of horsepower.

The breakdown of the engine code is as follows:

  • M – M-series
  • 8 – 8.0 HP horsepower
  • Suffix (engine is available with the following options):
    S – Electric starter;
    T – Retractable starter;
    ST – Electric and retractable starter;
    G – Tapered crankshaft (Generator applications);
    P – Threaded crankshaft (Pump applications);
    R – Reduction gear unit;
    EP – Generator;

General information

Engine Specifications
ModelMagnum M8
Type4-stroke, L-head, single cylinder
Displacement305 cm 3 (18.64 cu-in)
Max. horsepower8.2 PS (6.0 KW; 8.0 HP) at 3,600 rpm
Max. torque (crank PTO)
Fuel systemSide-draft carburetor
Cooling systemForced-air
Ignition systemElectronic magneto ignition system
Lubricating systemSplash type
Starting systemRecoil or electric starter
Fuel usedUnleaded gasoline (octane number 86 or higher)
Fuel tank capacity4.7 liters (1.25 US gal, 1.0 Imp. gal)
Weight32.2 kg (71.0 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio:6.8:1
Bore x Stroke74.7 X 69.85 mm (2.94 x 2.75 in)
Sleeve internal diameter74.5998-74.6252 mm (2.9370-2.9370 in)
Number of piston rings (compression / oil):2 / 1
Style A
Piston skirt outer diameter74.3737-74.4144 mm (2.9281-2.9297 in)
Ring end gapTop0.178-0.432 mm (0.007-0.017 in)
Second0.178-0.432 mm (0.007-0.017 in)
Style C and D
Piston skirt outer diameter74.4957-74.5134 mm (2.9329-2.9336 in)
Ring end gapTop0.254-0.584 mm (0.010-0.023 in)
Second0.254-0.584 mm (0.010-0.023 in)
Connecting rod small end ID15.8877-15.8953 mm (0.6255-0.6258 in)
Piston pin outer diameter15.8674-15.8725 mm (0.6247-0.6249 in)
Cylinder Head
Valve Arrangement:L-head (sidevalve)
Valve minimum lift – Zero lash:INTAKE6.90 mm (0.2718 in)
EXHAUST6.30 mm (0.2482 in)
Stem outer diameter (standard):INTAKE7.887-7.899 mm (0.3105-0.3110 in)
EXHAUST7.833-7.851 mm (0.3084-0.3091 in)

Tightening torque specs

Tightening torque specs
Cylinder head bolt34-41 Nm; 3.5-4.2 kg·m; 25-30 ft·lb
Spark plug25-30 Nm; 2.55-3.06 kg·m; 18-22 ft·lb

Service Information

Max speed3,600 rpm
Valve clearance
Intake valve clearance0.15-0.20 mm (0.0060-0.0079 in)
Exhaust valve clearance0.43-0.48 mm (0.0169-0.0189 in)
Oil system
Oil typeAPI SF or SG
Recommended oil Summer: SAE 30W
Winter: SAE 5W-20, 5W-30
Oil capacity0.95 liters (1 US.qts, 0.84 Imp. qts)
Ignition system
Spark plugChampion: RCJ-8
Spark plug gap0.65 mm (0.0256 in)
Ignition module air gap0.30-0.40 mm (0.012-0.016 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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We try to use verified sources and official documentation, however, differences between sources or errors in entering information may occur. We do not provide advice on technical issues related to the engines operation or repair. We do not recommend using provided information for engines repairing engines or spare parts ordering, use only official service manuals and spare-parts catalogs.

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