Honda G80

Honda G80The Honda G80 is a 296 cc (18.1 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.

It has an 80.0 mm (3.15 in) cylinder bore and 59.0 mm (2.32 in) piston stroke. The compression ratio rating is 6.3:1.

The Honda G80 engine produced 8.0 PS (5.9 kW; 7.9 HP) at 4,000 rpm of maximum output power and 16.0 N·m (1.6 kg·m, 11.8 ft·lb) at 2,500 rpm of peak torque.

The Honda G80 features:

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

General information

Engine Specifications
Engine model G80
Engine type 4-stroke, L-head, single-cylinder
Displacement 296 cm3, (18.1 cu·in)
Max. horsepower 8.0 PS (5.9 kW; 7.9 HP) at 4,000 rpm
Max. torque 16.0 N·m (1.6 kg·m, 11.8 ft·lb) at 2,500 rpm
Cooling system Forced air
Air cleaner Semi-dry type
Oil bath type
Lubricating system Splash type
Ignition system Flywheel magneto
Fuel system Horizontal type carburetor with butterfly valve
Fuel consumption 285 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 starting
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 30.0 kg (66.1 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio: 6.3:1
Cylinder bore: 80.0 mm (3.15 in)
Piston stroke: 59.0 mm (2.32 in)
Cylinder internal diameter (standard): 80.000 mm (3.1496 in)
Piston skirt outer diameter (standard): 79.970 mm (3.1484 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)
Ring width (Oil): 2.490 mm (0.098 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

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 (10 mm bolt) 35-40 Nm; 3.5-4.0 kg·m; 25.3-28.9 ft·lb
Cylinder Head (10 mm bolt) 35-40 Nm; 3.5-4.0 kg·m; 25.3-28.9 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
Muffler (8 mm bolt) 20-28 Nm; 2.0-2.8 kg·m; 14.5-20.2 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: 1.1 L (1.16 US. qt, 0.97 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)

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