The Honda G300 is a 272 cc (16.6 cu·in) natural aspirated single-cylinder four-stroke air-cooled internal combustion small gasoline engine with a horizontal shaft, manufactured by Honda Motor Company for general-purpose applications.
A 76.0 mm (2.99 in) cylinder bore and 60.0 mm (2.36 in) piston stroke give the G300 engine a total of 272 cc of displacement. The compression ratio rating is 6.5:1.
The Honda G300 engine produced 7.1 PS (5.2 kW; 7.0 HP) at 3,600 rpm of maximum output power and 15.0 N·m (1.5 kg·m, 11.1 ft·lb) of peak torque.
The Honda G300 features:
- L-head design
- Transistorized magneto or contact point breaker (CDI) ignition system
- Horizontal type carburetor with butterfly valve
- Centrifugal govervor
- Splash lubrication system
- Forced air cooling system
- Recoil or electric starter
General information
| Engine Specifications | |
| Engine model | G300 |
| Engine type | 4-stroke, L-head, single-cylinder |
| Displacement | 272 cm3, (16.6 cu·in) |
| Max. horsepower | 7.1 PS (5.2 kW; 7.0 HP) at 3,600 rpm |
| Max. torque |
Crankshaft PTO: 15.0 N·m (1.5 kg·m, 11.1 ft·lb) Camshaft PTO: 29.0 N·m (3.0 kg·m, 12.7 ft·lb) 1/2 reduction: 29.0 N·m (3.0 kg·m, 12.7 ft·lb) 1/6 reduction: 88.0 N·m (9.0 kg·m, 65.1 ft·lb) |
| Cooling system | Forced air |
| Air cleaner |
Semi-dry type Dry type Oil bath type |
| Lubricating system | Splash type |
| Ignition system | Transistorized magneto or contact point breaker (CDI) |
| Fuel system | Horizontal type carburetor with butterfly valve |
| Fuel consumption | 285 g/HPh |
| Fuel tank capacity | 6.0 L (1.59 US. gal. 1.32 Imp. gal.) |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Starting system | Recoil or electric starter |
| 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: | 6.5:1 |
| Cylinder bore: | 76.0 mm (2.99 in) |
| Piston stroke: | 60.0 mm (2.36 in) |
| Cylinder internal diameter (standard): | 76.000-76.017 mm (2.9921-2.9928 in) |
| Piston skirt outer diameter (standard): | 75.970-76.000 mm (2.9909-2.9921 in) |
| Number of piston rings (compression / oil): | 2/1 |
| Connecting rod small end diameter (standard): | 16.005-16.020 mm (0.6301-0.6307 in) |
| Side clearance (Top): | 0.020-0.060 mm (0.0008-0.0024 in) |
| Side clearance (Second): | 0.010-0.050 mm (0.0004-0.002 in) |
| Side clearance (Oil): | 0.010-0.050 mm (0.0004-0.002 in) |
| Ring end gap (Top): | 0.200-0.400 mm (0.0079-0.0157 in) |
| Ring end gap (Second): | 0.200-0.400 mm (0.0079-0.0157 in) |
| Ring end gap (Oil): | 0.200-0.400 mm (0.0079-0.0157 in) |
| Ring width (Top): | 1.970-1.990 mm (0.0776-0.0783 in) |
| Ring width (Second): | 1.970-1.990 mm (0.0776-0.0783 in) |
| Ring width (Oil): | 3.970-3.990 mm (0.1563-0.1571 in) |
| Crankpin journal diameter: | 29.943-29.959 mm (1.1789-1.1795 in) |
| Cylinder head | |
| Valve arrangement: | L-head |
| Valves: | 2 |
| Valve steam diameter (INTAKE): | 6.955-6.970 mm (0.2738-0.2744 in) |
| Valve steam diameter (EXHAUST): | 6.910-6.925 mm (0.272-0.2726 in) |
| Valve spring free length (INTAKE): | 42.7 mm (1.6811 in) |
| Valve spring free length (EXHAUST): | 42.7 mm (1.6811 in) |
| Camshaft lobe height (INTAKE): | 38.460-38.720 mm (1.5142-1.5244 in) |
| Camshaft lobe height (EXHAUST): | 38.460-38.720 mm (1.5142-1.5244 in) |
Tightening torque
| Tightening torque specs | |
| Fuel valve (12 mm) | 12-15 Nm; 1.2-1.5 kg·m; 8.7-10.8 ft·lb |
| Flywheel (16 mm) | 110-120 Nm; 11.0-12.0 kg·m; 80-87 ft·lb |
| Cylinder head | 24-26 Nm; 2.4-2.6 kg·m; 17-19 ft·lb |
| Tappet cover (6 mm) | 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb |
| Crankcase cover (8 mm) | 20-24 Nm; 2.0-2.4 kg·m; 15-17 ft·lb |
| Connecting rod | 12.6-15.4 Nm; 1.26-1.54 kg·m; 9.1-11 ft·lb |
| Fuel tank (8 mm) | 20-28 Nm; 2.0-2.8 kg·m; 15-20 ft·lb |
| Oil drain plug | 15-25 Nm; 1.5-2.5 kg·m; 11-18 ft·lb |
| Others | |
| 5 mm bolts, nuts | 4-7 Nm; 0.4-0.7 kg·m; 2.9-5.1 ft·lb |
| 6 mm bolts, nuts | 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb |
| 8 mm bolts, nuts | 20-28 Nm; 2.0-2.8 kg·m; 14.5-20.3 ft·lb |
| 10 mm bolts, nuts | 35-40 Nm; 3.5-4.0 kg·m; 25-29 ft·lb |
Service Data
| Idle speed: | 1,400±150 rpm |
| Cylinder compression: | 5.3 kg/cm2 (75 psi) |
| Valve clearance | |
| Intake valve clearance: | 0.08-0.16 mm (0.0031-0.0063 in) |
| Exhaust valve clearance: | 0.11-0.19 mm (0.0043-0.0075 in) |
| Oil system | |
| Lubrication system: | Splash |
| Oil type: | Honda 4-stroke “SE” |
| Recommended oil: | SAE 10W-40 |
| Oil capacity: | 1.2 L (1.27 US. qt, 1.06 Imp. qt.) |
| Reduction device oil capacity: |
1/2 reduction: 0.3 L (0.32 US. qt, 0.26 Imp. qt.) 1/6 reduction: 0.15 L (0.16 US. qt, 0.13 Imp. qt.) |
| Fuel system | |
| Type: | Horizontal type carburetor with butterfly valve |
| Main jet: | #88 |
| Float height: | 8.2 mm (0.3228 in) |
| Fuel tank capacity | 6.0 L (1.59 US. gal. 1.32 Imp. gal.) |
| Ignition system | |
| Type: | Transistorized magneto or contact point breaker (CDI) |
| Ignition timing: |
Magneto ignition: 20° B.T.D.C. The CDI type does not require adjustment |
| Spark plug: |
Magneto ignition: NGK B4H, BR4HS CDI ignition: NGK BP4HS-10, BPR4HS-10 |
| Spark plug gap: |
Magneto ignition: 0.6-0.7 mm (0.0236-0.0276 in) CDI ignition: 0.9-0.10 mm (0.0350-0.0390 in) |
Applications
| Manufacturer or Brand | Models |
| Generators | |
| Honda | E2500, EB2800 EB3000 |
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