The Onan B43E is a 710 cc (43.3 cu-in) two cylinder air-cooled four-stroke internal combustion small gasoline engine with horizontal shaft manufactured by Onan for general-purpose applications.
The B43E engine has an L-head design with two flat cylinders; carburetor fuel system and electric starter.
The cylinder bore is 82.55 mm (3.25 in) and the piston stroke is 66.55 mm (2.62 in), the compression ratio rating is 6.2:1. The Onan B43E engine produced 16.2 PS (11.9 kW; 16.0 HP) at 3,600 rpm of horsepower and 44.0 N·m (4.5 kg·m, 32.4 ft·lb) of torque.
General information
| Engine Specifications | |
| Model | Onan B43E |
| Type | 4-stroke, L-head, flat |
| Displacement | 710 cm3 (43.3 cu-in) |
| Max. horsepower | 16.0 HP (11.9 kW) at 3,600 rpm |
| Max. torque | 44.0 N·m (4.5 kg·m, 32.4 ft·lb) |
| Carburetor | – |
| Cooling system | Forced-air |
| Ignition system | – |
| Lubricating system | Forced lubrication |
| Starting system | Electric starter |
| PTO shaft rotation | Clockwise (viewed from flywhee) |
Cylinder Block and Head
| Cylinder block | ||
| Compression ratio: | 6.2:1 | |
| Bore x Stroke | 82.55 X 66.55 mm (3.25 x 2.62 in) | |
| Sleeve internal diameter | 82.530-82.550 mm (3.2492-3.25 in) | |
| Piston skirt outer diameter | 82.42-82.44 mm (3.2449-3.2457 in) | |
| Ring end gap | Top/Second | 0.250-0.510 mm (0.0098-0.0201 in) |
| Connecting rod small end ID | 17.470-17.480 mm (0.6878-0.6882 in) | |
| Piston pin outer diameter | 17.463-17.468 mm (0.6875-0.6877 in) | |
| Crankpin diameter | 41.280-41.300 mm (1.6252-1.626 in) | |
| Crankshaft main journal diameter | 50.780-50.800 mm (1.9992-2 in) | |
| Cylinder Head | ||
| Valve Arrangement: | L-haed | |
| Valves: | 4 (2 per cylinder) | |
| Stem outer diameter (standard): | INTAKE | 8.700-8.710 mm (0.3425-0.3429 in) |
| EXHAUST | 8.660-8.670 mm (0.3409-0.3413 in) | |
| Valve spring free length: | 42.210 mm (1.6618 in) | |
| Camshaft journal diameter: | 34.900-34.910 mm (1.374-1.3744 in) | |
| Lobe height: | INTAKE | 28.370-28.470 mm (1.1169-1.1209 in) |
| EXHAUST | 28.370-28.470 mm (1.1169-1.1209 in) | |
Service Information
| Engine | |
| Maximum speed | 3,600 |
| Cylinder compression | 517-793 kPa (75 to 115 psi) |
| Valve clearance | |
| Intake valve clearance | 0.130 mm (0.0051 in) |
| Exhaust valve clearance | 0.330 mm (0.013 in) |
| Oil system | |
| Recommended oil | SAE 10W-30 |
| Oil capacity |
With oil filter: 1.7 L (1.8 US. qt, 1.5 Imp. qt.) Without oil filter: 1.4 L (1.48 US. qt, 1.23 Imp. qt.) |
| Ignition system | |
| Ignition timing | 16° B.T.D.C. |
| Spark plug | NGK BPR5EF, Champion RS14YC |
| Spark plug gap | 0.640 mm (0.0252 in) |
| Breaker point gap | 0.410 mm (0.01610.0161 in)) |
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