Honda G65

Honda G65The Honda G65 is a 240 cc (14.65 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.

Cylinder bore and piston stroke are 72.0 mm (2.83 in) and 59.0 mm (2.32 in), respectively. The compression ratio rating is 6.1:1.

The G65 engine produced 6.8 PS (5.0 kW; 6.7 HP) at 4,000 rpm of maximum horsepower and 12.5 N·m (1.25 kg·m, 9 ft·lb) at 3,000 rpm of maximum torque.

The Honda G65 features:

  • L-head design
  • Flywheel magneto ignition system
  • Horizontal type carburetor with butterfly valve
  • Centrifugal govervor
  • Splash lubrication system
  • Forced air cooling system
  • Recoil starter or rope starter, starter motor for GS65 version

General information

Engine Specifications
Engine model G65 / GS65
Engine type 4-stroke, L-head, single-cylinder
Displacement 240 cm3, (14.65 cu·in)
Max. horsepower 6.8 PS (5.0 kW; 6.7 HP) at 4,000 rpm
Max. torque 12.5 N·m (1.25 kg·m, 9 ft·lb) at 3,000 rpm
Cooling system Forced air
Air cleaner Semi-dry type,
Oil bath type
Lubricating system Splash
Ignition system Flywheel magneto
Fuel system Horizontal type carburetor with butterfly valve
Fuel consumption 300 g/PSh
Fuel tank capacity 6.9 L (1.82 US. gal. 1.52 Imp. gal.)
Fuel used Unleaded gasoline (octane number 86 or higher)
Starting system Recoil starter or rope starter
GS65: Starter motor
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: 6.1:1
Cylinder bore: 72.0 mm (2.83 in)
Piston stroke: 59.0 mm (2.32 in)
Cylinder internal diameter (standard): 72.000 mm (2.8346 in)
Piston skirt outer diameter (standard): 71.970 mm (2.8335 in)
Number of piston rings (compression / oil): 2/1
Piston pin diameter: 19.000 mm (0.748 in)
Side clearance (Top): 0.020 mm (0.0008 in)
Side clearance (Second): 0.010 mm (0.0004 in)
Side clearance (Oil): 0.010 mm (0.0004 in)
Ring width (Top): 2.480 mm (0.0976 in)
Ring width (Second): 2.490 mm (0.098 in)
Crankshaft center distance: 29.5 mm (1.16 in)
Cylinder head
Valve arrangement: L-head
Valves: 2
Valve steam diameter (INTAKE): 6.970 mm (0.2744 in)
Valve steam diameter (EXHAUST): 6.930 mm (0.2728 in)
Camshaft lobe height (INTAKE): 35.180 mm (1.385 in)
Camshaft lobe height (EXHAUST): 35.180 mm (1.385 in)

Tightening torque specs

Tightening torque specs
Fuel tank (8 mm nut, bolt) 20-28 Nm; 2.0-2.8 kg·m; 14.5-20.2 ft·lb
Side cover (8 mm bolt) 20-25 Nm; 2.0-2.5 kg·m; 14.5-18.1 ft·lb
Cylinder Head (8 mm bolt) 20-25 Nm; 2.0-2.5 kg·m; 14.5-18.1 ft·lb
Cylinder (6 mm bolt) 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb
Cylinder (8 mm bolt) 20-28 Nm; 2.0-2.8 kg·m; 14.5-20.2 ft·lb
Camshaft center (6 mm bolt) 10-15 Nm; 1.0-1.5 kg·m; 7.2-10.8 ft·lb
Starter pulley (6 mm bolt) 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb
Flywheel (17 mm nut) 70-80 Nm; 7.0-8.0 kg·m; 50.6-57.9 ft·lb
Muffler (6 mm nut) 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb
Carburetor (6 mm nut) 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb

Service Data

Cylinder compression: 4.0 kg/cm2 at 450-600 rpm
Valve clearance
Intake valve clearance: 0.06-0.11 mm (0.0024-0.0043 in)
Exhaust valve clearance: 0.06-0.11 mm (0.0024-0.0043 in)
Oil system
Lubrication system: Splash type
Oil type: Honda 4-stroke or an equivalent (SG, SF)
Recommended oil: SAE 10W-30, 10W-40
Oil capacity: 0.82 L (0.87 US. qt, 0.72 Imp. qt.)
Fuel system
Type: Horizontal type carburetor with butterfly valve
Fuel tank capacity 6.9 L (1.82 US. gal. 1.52 Imp. gal.)
Ignition system
Type: Flywheel magneto
Ignition timing: 25° B.T.D.C (Fixed)
Spark plug: NGK BR6HS, B6HS
Spark plug gap: 0.6-0.7 mm (0.0236-0.0276 in)

1 Comment

  1. Have a honda g65 generator carburetor has been stripped down and in a box in bits. I can’t work out which way the jet ports go. Main no problem it is the little short ones that I am not sure about. Please can you help me with this. REGARDS Charles Baty.

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