The Honda G80 is a 296 cc (18.0 cu.in.) single-cylinder, air-cooled, four-stroke internal combustion small gasoline engine manufactured by Honda Motor Company since 1975 for general-purpose applications.
The Honda G80 engine has a slide valve (L-head) design and camshaft driven by a single row chain driven by the crankshaft. The engine has a recoil starter, horizontal carburetor with butterfly valve and high voltage ignition.
An 80.0 mm (3.2 in) cylinder bore and 59.0 mm (2.3 in) piston stroke give the engine a total of 296 cc (18.0 cu.in.) of displacement. The compression ratio was 6.3:1. The G80 produced 8.0 PS (5.9 KW; 7.9 HP) at 4,000 rpm of maximum horsepower and continuous rated output was 6.1 PS (4.5 KW; 6.0 HP) at 3,600 rpm. The maximum torque was 15.7 Nm (1.6 kg·m; 11.6 lbf·ft) at 2,500 rpm. The dry weight of the Honda G80 engine was 30.4 kg (67.0 lbs).
General information
Engine Specifications
Model
G80
Type
4-stroke, side valve type (L-head), single cylinder
Displacement
296 cm 3 (18.0 cu-in)
Max. horsepower
8.0 PS (5.9 KW; 7.9 HP) at 4,000 rpm
Max. torque
15.7 Nm (1.6 kg·m; 11.6 lbf·ft) at 2,500 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 liters (7.3 US.qts, 6.1 Imp. qts)
Fuel consumption
285 g/HPh
PTO shaft rotation
Counterclockwise (from PTO shaft side)
Cylinder Block and Head
Cylinder block
Compression ratio:
6.3:1
Bore x Stroke
80 X 59 mm (3.2 x 2.3 in)
Sleeve internal diameter
80.00 mm (3.150 in)
Piston skirt outer diameter
79.97 mm (3.148 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
1.1 liters (2.3 US pt, 1.9 lmp 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 (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
1 Comment
Thank you for compiling this wealth of technical information and publishing it on this site. It is very, very useful. Such information is also becoming increasingly harder to find, in general, as the years pass. Your site is a fine example of what the Internet *should* have become. Conversely, It has sadly become all but worthless in recent years. But it’s nice to know that some folks are still doing things right.
I’m definitely going to bookmark this site, as I work on sll manners and sizes of engines. Today it happens to be an old Honda G80… And, somehow I actually found your site, replete with all the information I needed. As such, I figured the least I could do was take a couple minutes to leave this message. Credit where due.
The Honda G80 is a 296 cc (18.0 cu.in.) single-cylinder, air-cooled, four-stroke internal combustion small gasoline engine manufactured by Honda Motor Company since 1975 for general-purpose applications.
Thank you for compiling this wealth of technical information and publishing it on this site. It is very, very useful. Such information is also becoming increasingly harder to find, in general, as the years pass. Your site is a fine example of what the Internet *should* have become. Conversely, It has sadly become all but worthless in recent years. But it’s nice to know that some folks are still doing things right.
I’m definitely going to bookmark this site, as I work on sll manners and sizes of engines. Today it happens to be an old Honda G80… And, somehow I actually found your site, replete with all the information I needed. As such, I figured the least I could do was take a couple minutes to leave this message. Credit where due.
Again, thank you.