The Onan B48G is a 0.8 L (782 cc, 47.7 cu·in) natural aspirated two-cylinders four-stroke air-cooled internal combustion small gasoline engine with a horizontal shaft, for general-purpose applications.
Cylinder bore and piston stroke are 82.55 mm (3.25 in) and 73.00 mm (2.87 in), respectively. The compression ratio rating is 7.0:1.
This engine produced 20.3 PS (14.9 kW; 20.0 HP) at 3,600 rpm of horsepower and 43.0 N·m (4.4 kg·m, 31.7 ft·lb) of torque.
The Onan B48G features:
- L-head design
- Automotive type battery ignition system ignition system
- Carburetor fuel system
- Forced lubrication system
- Air-cooling system
- Electric starter
General information
| Engine Specifications | |
| Engine model | B48G |
| Engine type | 4-stroke, L-head, two-cylinders |
| Displacement | 782 cm3, (47.72 cu·in) |
| Max. horsepower | 20.3 PS (14.9 kW; 20 HP) at 3,600 rpm |
| Max. torque | 43.0 N·m (4.4 kg·m, 31.7 ft·lb) |
| Cooling system | Forced air |
| Air cleaner | – |
| Lubricating system | Forced lubrication |
| Ignition system | Automotive type battery ignition system |
| Fuel system | Carburetor |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Starting system | Electric starter |
| Dimensions (L x W X H) | – |
| Dry weight | – |
Cylinder Block and Head
| Cylinder block | |
| Compression ratio: | 7.0:1 |
| Cylinder bore: | 82.55 mm (3.25 in) |
| Piston stroke: | 73.00 mm (2.87 in) |
| Cylinder internal diameter (standard): | 82.530-82.550 mm (3.2492-3.25 in) |
| Piston skirt outer diameter (standard): | 82.42-82.44 mm (3.2449-3.2457 in) |
| Number of piston rings (compression / oil): | 2/1 |
| Connecting rod small end diameter (standard): | 17.470-17.480 mm (0.6878-0.6882 in) |
| Piston pin diameter: | 17.463-17.468 mm (0.6875-0.6877 in) |
| Ring end gap (Top): | 0.250-0.510 mm (0.0098-0.0201 in) |
| Ring end gap (Second): | 0.250-0.510 mm (0.0098-0.0201 in) |
| Number of main bearings: | 2 |
| Crankshaft main journal diameter: | 50.780-50.800 mm (1.9992-2 in) |
| Crankpin journal diameter: | 41.280-41.300 mm (1.6252-1.626 in) |
| Crankshaft center distance: | 36.5 mm (1.435 in) |
| Cylinder head | |
| Valve arrangement: | L-head, gear driven |
| Valves: | 2 (4 valves in total) |
| Valve steam diameter (INTAKE): | 8.700-8.710 mm (0.3425-0.3429 in) |
| Valve steam diameter (EXHAUST): | 8.660-8.670 mm (0.3409-0.3413 in) |
| Valve spring free length (INTAKE): | 42.210 mm (1.6618 in) |
| Valve spring free length (EXHAUST): | 42.210 mm (1.6618 in) |
| Camshaft lobe height (INTAKE): | 29.570-29.720 mm (1.1642-1.1701 in) |
| Camshaft lobe height (EXHAUST): | 29.440-29.590 mm (1.1591-1.165 in) |
| Camshaft journal diameter : | 34.900-34.910 mm (1.374-1.3744 in) |
Service Data
| Cylinder compression: | 517-793 kPa (75 to 115 psi) |
| Valve clearance | |
| Intake valve clearance (COLD): | 0.130 mm (0.0051 in) |
| Exhaust valve clearance (COLD): | 0.330 mm (0.013 in) |
| Oil system | |
| Lubrication system: | Forced lubrication |
| Oil type: | SF, SF/CC, or SF/CD |
| Recommended oil: | SAE 10W-30 |
| Oil capacity: |
Without oil filter: 1.4 L (1.48 US. qt, 1.23 Imp. qt.) With oil filter: 1.7 L (1.8 US. qt, 1.5 Imp. qt.) |
| Fuel system | |
| Type: | Carburetor |
| Ignition system | |
| Type: | Automotive type battery ignition system |
| Ignition timing: |
Spec A&B: 20° B.T.D.C. Spec C: 16° B.T.D.C. |
| Spark plug: | NGK BPR5EF, Champion RS14YC |
| Spark plug gap: | 0.640 mm (0.0252 in) |
| Ignition coil air gap |
Spec A&B: 0.530 mm (0.020 in) Spec C: 0.410 mm (0.016 in) |
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