The Honda G50 is a 187 cc, (11.4 cu·in) natural aspirated single-cylinder four-stroke air-cooled internal combustion small gasoline engine with a horizontal shaft, manufactured by Honda Motor Company for general-purpose applications.
The cylinder bore is 69.0 mm (2.72 in) and the piston stroke is 50.0 mm (1.97 in). The compression ratio rating is 6.5:1 for the G50K1 version or 6.9:1 for the Honda G50K2.
The G50 engine produced 3.8 PS (2.8 kW; 3.8 HP) at 3,600 rpm of continuous rated horsepower or 5.0 PS (3.67 kW; 4.9 HP) at 4,000 rpm of maximum output power and 9.0 N·m (0.9 kg·m, 6.6 ft·lb) at 3,600 rpm of maximum torque.
The Honda G50 features:
- L-haed design
- High voltage ignition system
- Horizontal type carburetor with butterfly valve
- Centrifugal govervor
- Splash type lubrication system
- Forced air cooling system
- Recoil starter
General information
Engine Specifications | |
Engine model | G50 |
Engine type | 4-stroke, L-head, single-cylinder |
Displacement | 187 cm3, (11.4 cu·in) |
Max. horsepower | 5.0 PS (3.67 kW; 4.9 HP) at 4,000 rpm |
Max. torque | 9.0 N·m (0.9 kg·m, 6.6 ft·lb) at 3,600 rpm |
Cooling system | Forced air |
Air cleaner | Oil bath type |
Lubricating system | Splash |
Ignition system | High voltage ignition |
Fuel system | Horizontal type carburetor with butterfly valve |
Fuel consumption | 300 g/HPh |
Fuel tank capacity |
G50: 6.0 L (1.6 US gal. 1.3 Imp. gal.) G50K1: 3.4 L (0.9 US gal. 0.7 Imp. gal.) G50K2: 4.0 L (1.1 US gal. 0.9 Imp. gal.) |
Fuel used | Unleaded gasoline (octane number 86 or higher) |
Starting system | Recoil starter |
Stoping system | Ignition primary circuit ground |
Governor | Centrifugal govervor |
PTO shaft rotation | Counterclockwise (from PTO shaft side) |
Dimensions (L x W X H) | – |
Dry weight | – |
Cylinder Block and Head
Cylinder block | |
Compression ratio: |
G50K1: 6.5:1 G50K2: 6.9:1 |
Cylinder bore: | 69.0 mm (2.72 in) |
Piston stroke: | 50.0 mm (1.97 in) |
Cylinder internal diameter (standard): | 69.000 mm (2.7165 in) |
Piston skirt outer diameter (standard): | 68.970-68.990 mm (2.7153-2.7161 in) |
Number of piston rings (compression / oil): | 2/1 |
Connecting rod small end diameter (standard): | 18.010-18.030 mm (0.7091-0.7098 in) |
Side clearance (Top): | 0.020-0.060 mm (0.0008-0.0024 in) |
Side clearance (Second): | 0.020-0.060 mm (0.0008-0.0024 in) |
Side clearance (Oil): | 0.020-0.060 mm (0.0008-0.0024 in) |
Ring end gap (Top): | 0.200-0.400 mm (0.0079-0.0157 in) |
Ring end gap (Second): | 0.200-0.400 mm (0.0079-0.0157 in) |
Ring end gap (Oil): | 0.200-0.400 mm (0.0079-0.0157 in) |
Cylinder head | |
Valve arrangement: | L-head |
Valves: | 2 |
Valve steam diameter (INTAKE): | 6.970 mm (0.2744 in) |
Valve steam diameter (EXHAUST): | 6.925 mm (0.2726 in) |
Valve spring free length (INTAKE): | 27.9 mm (1.0984 in) |
Valve spring free length (EXHAUST): | 27.9 mm (1.0984 in) |
Camshaft journal diameter : | 11.966-11.984 mm (0.4711-0.4718 in) |
Tightening torque specs
Tightening torque specs | |
Cylinder head (8×1.25 mm) | 20-24 Nm; 2.0-2.4 kg·m; 14.5-17.4 ft·lb |
Flywheel (14×1.25 mm) | 80-90 Nm; 8.0-9.0 kg·m; 57.9-65.1 ft·lb |
Fuel tank (6×1.0 mm) | 10-12 Nm; 1.0-1.2 kg·m; 7.2-8.7 ft·lb |
Fuel tank (8×1.25 mm) | 24-28 Nm; 2.4-2.8 kg·m; 17.4-20.3 ft·lb |
Muffler (6×1.0 mm) | 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb |
Starter pulley (6×1.0 mm) | 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb |
Fuel cock (6×1.0 mm) | 10-12 Nm; 1.0-1.2 kg·m; 7.2-8.7 ft·lb |
PTO (8×1.25 mm) | 20-24 Nm; 2.0-2.4 kg·m; 14.5-17.4 ft·lb |
Carburetor (6×1.0 mm) | 10-12 Nm; 1.0-1.2 kg·m; 7.2-8.7 ft·lb |
Others | |
5×0.8 mm screw, bolt, nut | 3.5-6.5 Nm; 0.35-0.65 kg·m; 2.5-4.7 ft·lb |
6×1.0 mm bolt | 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb |
8×1.25 mm bolt | 20-28 Nm; 2.0-2.8 kg·m; 14.5-20.3 ft·lb |
10×1.25 mm bolt | 40-50 Nm; 4.0-5.0 kg·m; 28.9-36.2 ft·lb |
Service Data
Cylinder compression: |
G50K1: 7.0 kg/cm2 at 750 rpm G50K2: 6.0 kg/cm2 at 1,000 rpm |
Valve clearance | |
Intake valve clearance: | 0.07 mm (0.0028 in) |
Exhaust valve clearance: | 0.07 mm (0.0028 in) |
Oil system | |
Lubrication system: | Splash |
Oil type: | 4-stroke Honda engine oil |
Recommended oil: | SAE 10W-40 |
Oil capacity: | 0.6 L (0.63 US. qt, 0.53 Imp. qt.) |
Fuel system | |
Type: | Horizontal type carburetor with butterfly valve |
Fuel tank capacity |
G50: 6.0 L (1.6 US gal. 1.3 Imp. gal.) G50K1: 3.4 L (0.9 US gal. 0.7 Imp. gal.) G50K2: 4.0 L (1.1 US gal. 0.9 Imp. gal.) |
Ignition system | |
Type: | High voltage ignition |
Ignition timing: | 20° B.T.D.C. (Fixed) |
Spark plug: |
G50: NGK B-6H G50K1: – NGK B-6HS G50K2: – NGK B-6HS, BR-6HS |
Spark plug gap: | 0.6-0.7 mm (0.0236-0.0276 in) |
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