The Honda G42 is a 171 cc, (10.44 cu·in) natural aspirated single-cylinder four-stroke air-cooled internal combustion small gasoline engine with a horizontal shaft, manufactured by Honda Motor Company from 1972 for general-purpose applications.
The Honda G42 engine has a single-cylinder, slide valve (L-head) design, and camshaft driven by a single row chain driven by the crankshaft. It used a recoil starter, horizontal carburetor with butterfly valve, and high voltage ignition system. The engine is fitted with an oil bath-type air cleaner and a 3.4 L (0.9 US. gal. 0.75 Imp. gal.) fuel tank.
The G42 engine produced 3.3 PS (2.42 kW; 3.2 HP) at 3,400 rpm of continuous rated power, 4.5 PS (3.3 kW; 4.4 HP) at 4,000 rpm of maximum horsepower, and 8.3 N·m (0.8 kg·m, 6.1 ft·lb) at 3,600 rpm of peak torque.
General information
Engine Specifications | |
Engine model | G42 |
Engine type | 4-stroke, L-head, single-cylinder |
Displacement | 171 cm3, (10.44 cu·in) |
Max. horsepower | 4.5 PS (3.3 kW; 4.4 HP) at 4,000 rpm/td> |
Max. torque | 8.3 N·m (0.8 kg·m, 6.1 ft·lb) at 3,600 rpm |
Cooling system | Forced air |
Air cleaner | Oil bath type |
Lubricating system | Splash type |
Ignition system | High-voltage ignition |
Fuel system | Horizontal type carburetor with butterfly valve |
Fuel consumption | 300 g/HPh |
Fuel tank capacity |
G42 – 3.4 L (0.9 US gal. 0.7 Imp. gal.) G42K1 – 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) | 425 x 325 x 430 mm (16.7 x 12.8 x 16.9 in) |
Dry weight | 19.0 kg (41.9 lbs) |
Cylinder Block and Head
It has a 66.0 mm (2.6 in) cylinder bore and 50.0 mm (1.97 in) piston stroke. The compression ratio rating is 6.4:1.
Cylinder block | |
Compression ratio: | 6.4:1 |
Cylinder bore: | 66.0 mm (2.6 in) |
Piston stroke: | 50.0 mm (1.97 in) |
Cylinder internal diameter (standard): | 66.000 mm (2.5984 in) |
Piston skirt outer diameter (standard): | 65.970-65.980 mm (2.5972-2.5976 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) |
Piston pin diameter: | 17.994-18.000 mm (0.7084-0.7087 in) |
Side clearance (Top): | 0.030-0.070 mm (0.0012-0.0028 in) |
Side clearance (Second): | 0.030-0.070 mm (0.0012-0.0028 in) |
Side clearance (Oil): | 0.030-0.070 mm (0.0012-0.0028 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 lobe lift (INTAKE): | 5.8 mm (0.2283 in) |
Camshaft lobe liift (EXHAUST): | 5.8 mm (0.2283 in) |
Camshaft journal diameter: | 11.953-11.968 mm (0.4706-0.4712 in) |
Service Data
The Honda 4-stroke or an equivalent oil with a viscosity of SAE 10W-30 or 10W-40 is recommended for the Honda G42 engine, refilling oil capacity is 0.6 L (0.63 US. qt, 0.53 Imp. qt.).
Compression pressure | |
Standard: | 0.6 kg/cm2 |
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 type |
Oil type: | SAE 10W-30 or 10W-40 |
Recommended oil: | Honda 4-stroke or an equivalent |
Oil capacity: | 0.6 L (0.63 US. qt, 0.53 Imp. qt.) |
Fuel system | |
Type: | Horizontal type carburetor with butterfly valve |
Ignition system | |
Type: | High-voltage ignition |
Ignition type: | 20° B.T.D.C. |
Spark plug: |
G42 – NGK: B-6HS G42K1 – NGK: B-6HS, BR-6HS |
Spark plug gap: | 0.6-0.7 mm (0.0236-0.0276 in) |
Applications
Manufacturer or Brand | Models |
Tillers | |
Honda | F42 |
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