Honda GS65

Honda GS65The Honda GS65 is a 240 cc, (14.6 cu·in) natural aspirated single-cylinder four-stroke air-cooled internal combustion small gasoline engine with a horizontal shaft, manufactured by Honda Motor Company since 1975 for general-purpose applications.

The cylinder bore is 72.0 mm (2.83 in) and the piston stroke is 59.0 mm (2.32 in). The compression ratio rating is 6.1:1.

This engine produced 6.8 PS (5.0 kW; 6.7 HP) at 4,000 rpm of horsepower and 12.0 N·m (1.2 kg·m, 8.8 ft·lb) at 3,000 rpm of torque.

The Honda GS65 features:

  • OHV design
  • High voltage ignition system
  • Horizontal type carburetor with butterfly valve
  • Centrifugal governor
  • Splash type lubrication system
  • Forced air cooling system
  • Electric starter

General information

Engine Specifications
Engine model GS65
Engine type 4-stroke, OHV, single-cylinder
Displacement 240 cm3, (14.6 cu·in)
Max. horsepower 6.8 PS (5.0 kW; 6.7 HP) at 4,000 rpm
Max. torque 12.0 N·m (1.2 kg·m, 8.8 ft·lb) at 3,000 rpm
Cooling system Forced air
Air cleaner
Lubricating system Splash system
Ignition system High voltage ignition
Fuel system Horizontal type carburetor with butterfly valve
Fuel consumption 300 g/HPh
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 Electric starter
Stoping system Ground switch
Governor Centrifugal governor
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): 72.00 mm (2.8346 in)
Piston skirt outer diameter (standard): 71.97 mm (2.8335 in)
Number of piston rings (compression / oil): 2/1
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)
Ring width (Oil): 2.490 mm (0.098 in)
Crankshaft center distance: 29.5 mm (1.16 in)
Cylinder head
Valve arrangement: OHV
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

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 system
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.)
Ignition system
Type: High voltage ignition
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)

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