Kohler M12

The Kohler M12 is a 476.4 cc (29.07 cu·in) single-cylinder air-cooled four-stroke internal combustion gasoline engine from the Magnum-series, manufactured by Kohler Co.

The Kohler M12 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 M12 engine used a high-density paper air cleaner.

The cylinder bore is 85.85 mm (3.38 in) and the piston stroke is 82.6 mm (3.25 in). The compression ratio rating is 6.6:1.

The Kohler M12 engine produced 12.1 PS (8.9 KW; 12.0 HP) at 3,600 rpm of horsepower.

The breakdown of the engine code is as follows:

• M – M-series
• 12 – 12.0 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
Model	M12
Type	4-stroke, L-head, single cylinder
Displacement	476.4 cm 3 (29.07 cu-in)
Max. horsepower	12.1 PS (8.9 KW; 12.0 HP) at 3,600 rpm
Max. torque (crank PTO)	–
Fuel system	Side-draft carburetor
Cooling system	Forced-air
Ignition system	Electronic magneto ignition system
Lubricating system	Splash type
Starting system	Recoil or electric starter
Fuel used	Unleaded gasoline (octane number 86 or higher)
Fuel tank capacity	5.7 liters (1.5 US gal, 1.3 Imp. gal)
Weight	58.5 kg (129 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio:		6.6:1
Bore x Stroke		85.8 X 82.6 mm (3.38 x 3.25 in)
Sleeve internal diameter		85.7123-85.7377 mm (3.3745-3.3755 in)
Piston skirt outer diameter		85.4710-85.5472 mm (3.3650-3.3680 in)
Number of piston rings (compression / oil):		2 / 1
Ring end gap	Top	0.254-0.508 mm (0.010-0.020 in)
	Second	0.254-0.508 mm (0.010-0.020 in)
Connecting rod small end ID		22.2428-2.2505 mm (0.8757-0.8760 in)
Piston pin outer diameter		22.2377-22.2351 mm (0.8752-0.8754 in)
Cylinder Head
Valve Arrangement:		L-head (sidevalve)
Valves:		2
Valve minimum lift – Zero lash:	INTAKE	8.07 mm (0.318 in)
	EXHAUST	8.07 mm (0.318 in)
Stem outer diameter (standard):	INTAKE	7.887-7.899 mm (0.3105-0.3110 in)
	EXHAUST	7.833-7.851 mm (0.3084-0.3091 in)

Tightening torque specs

Tightening torque specs
Cylinder head bolt	34-41 Nm; 3.5-4.2 kg·m; 25-30 ft·lb
Spark plug	25-30 Nm; 2.55-3.06 kg·m; 18-22 ft·lb

Service Information

Engine
Max speed	3,600 rpm
Valve clearance
Intake valve clearance	0.20-0.25 mm (0.0079-0.0098 in)
Exhaust valve clearance	0.43-0.48 mm (0.0169-0.0189 in)
Oil system
Oil type	API SF or SG
Recommended oil	Summer: SAE 30W Winter: SAE 5W-20, 5W-30
Oil capacity	1.9 L (2.0 US. qt, 1.67 Imp. qt.)
Ignition system
Spark plug	Champion: RH10
Spark plug gap	0.65 mm (0.0256 in)
Ignition module air gap	0.30-0.40 mm (0.012-0.016 in)