Kohler M18

Kohler M18The Kohler M18 is a 691 cc (41.2 cu·in) two-cylinder air-cooled four-stroke internal combustion gasoline engine from the Magnum-series, manufactured by Kohler Co.

The Kohler M18 engine has an L-head (side valve) design and a horizontal PTO shaft. This engine is equipped with the Kohler or Walbro-build carburetor and an electronic magneto ignition system. The M18 engine used a high-density paper air cleaner.

The cylinder bore is 79.0 mm (3.11 in) and the piston stroke is 70.0 mm (2.76 in). The compression ratio rating is 6.0:1. This engine produced 18.2 PS (13.4 kW; 18.0 HP) at 3,600 rpm of horsepower.

The breakdown of the engine code is as follows:

  • M – M-series
  • 18 – 18.0 HP horsepower
  • Suffix (engine is available with the following options):
    S – Electric starter;
    G – Tapered crankshaft (Generator applications);
    P – Threaded crankshaft (Pump applications);
    EP – Generator;
    Q – Quilet model;

General information

Engine Specifications
Type4-stroke, L-head, two-cylinder
Displacement691 cm 3 (41.2 cu-in)
Max. horsepower18.2 PS (13.4 kW; 18.0 HP) at 3,600 rpm
Max. torque (crank PTO)
Fuel systemCarburetor
Cooling systemForced-air
Ignition systemElectronic magneto ignition system
Lubricating systemSplash type
Starting systemElectric starter
Fuel usedUnleaded gasoline (octane number 86 or higher)
Fuel tank capacity5.5 L (1.45 US. gal. 1.21 Imp. gal.)

Cylinder Block and Head

Cylinder block
Compression ratio:
Bore x Stroke79.0 mm X 70.0 mm (3.11 x 2.76 in)
Sleeve internal diameter79.050-79.075 mm (3.1122-3.1132 in)
Piston skirt outer diameter78.944-78.961 mm (3.108-3.1087 in)
Number of piston rings (compression / oil):2 / 1
Ring end gapTop0.253-0.582 mm (0.010-0.023 in)
Second0.253-0.582 mm (0.010-0.023 in)
Connecting rod small end ID15.825-15.833 mm (0.623-0.6233 in)
Piston pin outer diameter15.805-15.810 mm (0.6222-0.6224 in)
Cylinder Head
Valve Arrangement:L-head (sidevalve)
Valve minimum lift – Zero lash:INTAKE6.9 mm (0.274 in)
EXHAUST6.9 mm (0.274 in)
Stem outer diameter (standard):INTAKE7.8506 mm (0.3091 in)
EXHAUST7.8126 mm (0.3076 in)

Tightening torque specs

Tightening torque specs
Cylinder head bolt20-37 Nm; 2.04-3.77 kg·m; 14.8-27.3 ft·lb
Spark plug18 N·m; 1.8 kg·m; 13.3 ft·lb

Service Information

Max speed3,600 rpm
Valve clearance
Intake valve clearance0.076-0.152 mm (0.003-0.006 in)
Exhaust valve clearance0.278-0.354 mm (0.0109-0.0139 in)
Oil system
Oil typeAPI SF or SG
Recommended oil Summer: SAE 30W
Winter: SAE 5W-20, 5W-30
Oil capacity (with filter)1.6 L (1.69 US. qt, 1.41 Imp. qt.)
Ignition system
Spark plugChampion: RV17YC
Spark plug gap0.89 mm (0.035 in)
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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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