Honda G65

The Honda G65 is a 240 cc single-cylinder air-coolled 4-stroke internal combustion small gasoline engine manufactured by Honda Motor Company since 1966 for general-purpose applications, such as: commercial lawn and garden equipment, tillers and cultivators, generators, construction and industrial equipment, agricultural equipment, small vehicles.

The Honda G65 engine has a slide valve (L-head) design and camshaft driven by a single row chain driven by the crankshaft. It has a recoil starter, horizontal carburetor with butterfly valve and high voltage ignition.

The G65 produced 6.8 HP (5.0 kW) at 4000 rpm and 12.2 Nm (1.24 kg·m) at 3000 rpm. The dry weight of the Honda G65 engine was 27.6 kg (61.7 lbs). A 72 mm (2.8 in) cylinder bore and 59 mm (2.3 in) piston stroke give the engine a total of 240 cc (14.6 cu.in.) of displacement. The compression ratio is 6.1:1.

General information

Engine Specifications
Model	G65
Type	4-stroke, side valve type (L-head), single cylinder
Displacement	240 cm 3 (14.6 cu-in)
Max. horsepower	6.8 HP (5.0 kW) at 4000 rpm
Max. torque	12.0 Nm (1.24 kg·m) at 3000 rpm
Carburetor	Horizontal, butterfly valve
Cooling system	Forced-air
Ignition system	High voltage ignition
Lubricating system	Splash system
Starting system	Recoil starter
Stoping system	Ground switch
Fuel used	Unleaded gasoline (octane number 86 or higher)
Fuel tank capacity	6.9 L (1.6 US gal., 1.5 Imp. gal.)
Fuel consumption	300 g/HPh (0.67 lb/HPh)
PTO shaft rotation	Counterclockwise (from PTO shaft side)

Cylinder Block and Head

Cylinder block
Compression ratio:		6.1:1
Bore x Stroke		72 X 59 mm (2.8 x 2.3 in)
Sleeve internal diameter		72.00 mm (2.835 in)
Piston skirt outer diameter		71.97 mm (2.833 in)
Ring width	Top	2.48 mm (0.098 in)
	Second/Oil	2.49 mm (0.098 in)
Ring Side Clearance	Top	0.02 mm (0.0008 in)
	Second/Oil	0.01 mm (0.0004 in)
Piston pin outer diameter		19.0 mm (0.748 in)
Cylinder Head
Warpage (max)		0.2 mm (0.01 in)
Valve Arrangement:		Side valve type (L-head)
Valves:		2
Stem outer diameter (standard):	INTAKE	6.97 mm (0.274 in)
	EXHAUST	6.93 mm (0.273 in)
Valve guide internal diameter		7.00 mm (0.276 in)
Cam height:	INTAKE	35.18 mm (1.385 in)
	EXHAUST	35.18 mm (1.385 in)

Maintenance data

Engine
Cylinder compression	4.0 kg/cm2 at 450-600 rpm
Tappet clearance
Intake valve	0.06-0.11 mm (0.0023-0.0043)
Exhaust valve	0.06-0.11 mm (0.0023-0.0043)
Oil system
Oil type	Honda 4-stroke or an equivalent (SG, SF)
Recommended oil	SAE 10W-30, 10W-40
Oil capacity	0.82 L (1.7 US pt., 1.4 Imp. pt.)
Ignition system
Ignition timing	25 ° B.T.D.C (Fixed)
Spark plug	NGK: BR6HS, B6HS
Spark plug gap	0.6-0.7 mm (0.024-0.028 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