The Kohler Magnum M20 is a 770 cc, (46.98 cu·in) natural aspirated two-cylinders four-stroke air-cooled internal combustion small gasoline engine with a horizontal shaft, for general-purpose applications.
Cylinder bore is 79.2 mm (3.12 in) and piston stroke is 77.7 mm (3.06 in). The compression ratio rating is 6.6:1. The Kohler M20 engine produced 20.3 PS (14.9 KW; 20.0 HP) at 3,600 rpm of maximum output power.
The Kohler M20 features:
- L-head design
- Electronic magneto ignition system
- Kohler or Walbro carburetor
- Centrifugal governor
- Full pressure lubrication system with oil filter
- Forced air cooling system
- Electric starter
General information
| Engine Specifications | |
| Engine model | Magnum M20 |
| Engine type | 4-stroke, L-head, V-twin |
| Displacement | 770 cm3, (46.98 cu·in) |
| Max. horsepower | 20.3 PS (14.9 KW; 20.0 HP) at 3,600 rpm |
| Max. torque | – |
| Cooling system | Forced air |
| Air cleaner | Replaceable, paper element |
| Lubricating system | Full pressure with oil filter |
| Ignition system | Electronic magneto ignition system |
| Fuel system | Kohler or Walbro carburetor |
| Fuel consumption | – |
| Fuel tank capacity | – |
| Fuel used | Gasoline (octane number 86 or higher) |
| Starting system | Electric starter, 12V |
| Governor | Centrifugal governor |
| PTO shaft rotation | Counterclockwise (from PTO shaft side) |
| Dimensions (L x W X H) | 341 x 448 x 440 mm (13.4 x 17.6 x 17.3 in) |
| Dry weight | 58.9 kg (130.0 lbs) |
Cylinder Block and Head
| Cylinder block | |
| Compression ratio: | 6.6:1 |
| Cylinder bore: | 79.2 mm (3.12 in) |
| Piston stroke: | 77.7 mm (3.06 in) |
| Cylinder internal diameter (standard): | 79.362-79.388 mm (3.1245-3.1255 in) |
| Piston skirt outer diameter (standard): | 79.256-79.273 mm (3.1203-3.1210 in) |
| Number of piston rings (compression / oil): | 2/1 |
| Piston pin diameter: | 19.047-19.052 mm (0.7499-0.7501 in) |
| Side clearance (Top): | 0.1518 mm (0.006 in) |
| Side clearance (Second): | 0.1518 mm (0.006 in) |
| Ring end gap (Top): | 0.2530-0.5820 mm (0.01-0.0229 in) |
| Ring end gap (Second): | 0.2530-0.5820 mm (0.01-0.0229 in) |
| Main bearing surface (max): | 44.213 mm (1.7407 in) |
| Crankpin outer diemeter: | 38.082-38.095 mm (1.4993-1.4998 in) |
| Cylinder head | |
| Valve arrangement: | L-head |
| Valves: | 2,(4 valves in total) |
| Valve head diameter (INTAKE): | 34.798-35.052 mm (1.370-1.380 in) |
| Valve head diameter (EXHAUST): | 34.798-35.052 mm (1.370-1.380 in) |
| Valve steam diameter (INTAKE): | 7.881 mm (0.3103 in) |
| Valve steam diameter (EXHAUST): | 7.843 mm (0.3088 in) |
| Valve Minimum Lift-Zero Lash (INTAKE): | 6.9 mm (0.274 in) |
| Valve Minimum Lift-Zero Lash (EXHAUST): | 6.9 mm (0.274 in) |
| Valve Guide I.D. (Max. Wear) (INTAKE): | 0.1265 mm (0.005 in) |
| Valve Guide I.D. (Max. Wear) (EXHAUST): | 0.1771 mm (0.007 in) |
Tightening torque settings:
- Cylinder Head: 20.0-27.0 Nm; 15.0-20.0 ft·lb;
- Connecting Rods (New): 16.0 Nm; 12.0 ft·lb;
- Connecting Rods (Used): 11.0 Nm; 8.3 ft·lb;
- Flywheel Screw: 54.0 Nm; 40.0 ft·lb;
- Manifold Screw/Nut: 17 Nm; 12.5 ft·lb;
- Fuel Pump Mounting Screws: 4.2-5.1 Nm; 3.1-3.8 ft·lb
- Ignition Module: 3.6 Nm; 2.7 ft·lb
- Spark Plugs: 18 Nm; 13.3 ft·lb
- Oil Filter: 5.7-9.1 Nm; 4.2-6.7 ft·lb
- Closure Plate: 17.0 Nm; 12.5 ft·lb
Service Data
| Valve clearance | |
| Intake valve clearance: | 0.076-0.152 mm (0.003-0.006 in) |
| Exhaust valve clearance: | S/n 1816500646 and earlier: 0.406-0.482 mm (0.016-0.019 in) S/n 1816500656 and later: 0.278-0.354 mm (0.011-0.014 in) |
| Oil system | |
| Lubrication system: | Full pressure with oil filter |
| Oil filter | Full-flow type |
| Oil type: | SF or SG |
| Recommended oil: | 5W-20, 5W-30, 10W-30, 10W-40 |
| Oil capacity: | With oil filter: 1.6 L (1.69 US. qt, 1.41 Imp. qt.) W/o oil filter: 1.4 L (1.48 US. qt, 1.23 Imp. qt.) |
| Oil pressure: | More then 3.5 kg/cm2, 50 psi |
| Fuel system | |
| Fuel pump type | Mechanical |
| Fuel filter type | In-line |
| Type: | Kohler or Walbro carburetor |
| Main fuel: | Kohler: 2-1/2 turns Walbro (fixed jet): Not adjust Walbro (adjustable jet): 1 turn |
| Low idle: | Kohler: 1 turn Walbro: 1-1/4 turns |
| Ignition system | |
| Type: | Electronic magneto ignition system |
| Spark plug: | Champion RV17YC |
| Spark plug gap: | 0.89 mm (0.035 in) |
| Spark plug torque: | 18 N·m (1.8 kg·m, 13.3 ft·lb) |
| Ignition coil air gap | 0.2-0.3 mm (0.0079-0.0118 in) |
References
1. Kohler Magnum M18, M20 V-twin engine service manual. Kohler Co.
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