
This engine has a single-cylinder, overhead-valve, and precision camshaft design, the high compression ratio for better fuel efficiency and a ball bearing supported crankshaft for greater stability. The Honda GXV50 engine has transistorized magneto ignition, horizontal type carburetor, and recoil starter.
A 41.8 mm (1.65 in) cylinder bore and 36.0 mm (1.42 in) piston stroke give the engine a total of 49 cc (2.99 cu-in) of displacement. Compression ratio rating is 8.0:1.
The GXV50 engine produces 2.5 PS (1.8 KW; 2.5 HP) at 7,000 rpm of maximum horsepower and 3.04 Nm (0.31 kg·m; 2.24 lbf·ft) at 4,500 rpm of peak torque.
General information
| Engine Specifications | |
| Model | GXV50 (vertical shaft) |
| Type | 4-stroke, OHV, single cylinder |
| Displacement | 49 cm 3 (2.99 cu-in) |
| Max. horsepower | 2.5 PS (1.8 KW; 2.5 HP) at 7,000 rpm |
| Max. torque (crank PTO) | 3.04 Nm (0.31 kg·m; 2.24 lbf·ft) at 4,500 rpm |
| Carburetor | Horizontal type, butterfly valve |
| Cooling system | Forced-air |
| Ignition system | Transistorized magneto ignition |
| Lubricating system | Splash |
| Starting system | Recoil or electric starter |
| Stoping system | Ignition primary circuit ground |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Fuel tank capacity | 0.5 liters (0.53 US.qts, 0.44 Imp. qts) |
| Fuel consumption | 250 g/HPh |
| PTO shaft rotation | Counterclockwise (from PTO shaft side) |
Dimensions and Weight
| S | V | |
| Length, mm (in) | 249 (9.8) | |
| Width, mm (in) | 286 (11.3) | |
| Height, mm (in) | 225 (8.9) | 198 (7.8) |
| Dry weight, kg (lb) | 5.2 (11.47) | |
| Operating weight, kg (lb) |
5.7 (12.57) | |
Cylinder Block and Head
| Cylinder block | ||
| Compression ratio: | 8.0:1 | |
| Bore x Stroke | 41.8 mm X 36.0 mm (1.65 x 1.42 in) | |
| Sleeve internal diameter | 41.800-41.815 mm (1.6457-1.6463 in) | |
| Piston skirt outer diameter | 41.770-41.790 mm (1.6445-1.6453 in) | |
| Piston ring side clearance (Top): | 0.015-0.050 mm (0.0006-0.0020 in) | |
| Piston ring side clearance (Second): | 0.015-0.050 mm (0.0006-0.0020 in) | |
| Piston ring end gap (Top): | 0.150-0.300 mm (0.0059-0.0118 in) | |
| Piston ring end gap (Second): | 0.150-0.300 mm (0.0059-0.0118 in) | |
| Ring width (Top): | 0.770-0.790 mm (0.030-0.031 in) | |
| Ring width (Second): | 0.970-0.990 mm (0.038-0.039 in) | |
| Connecting rod small end ID | 10.006-10.007 mm (0.3939-0.3944 in) | |
| Connecting rod big end ID | 15.000-15.011 mm (0.5906-0.5910 in) | |
| Crankpin outer diameter | 14.973-14.984 mm (0.5895-0.5899 in) | |
| Cylinder Head | ||
| Warpage (limit) | 0.10 mm (0.004 in) | |
| Valve Arrangement: | OHV | |
| Valves: | 2 | |
| Valve stem outer diameter (INTAKE): | 3.970-3.985 mm (0.1563-0.1569 in) | |
| Valve stem outer diameter (EXHAUST): | 3.935-3.950 mm (0.1549-0.1555 in) | |
| Spring free length | 23.7.0 mm (0.93 in) | |
| Cam height | 27.972 mm (1.1013 in) | |
Tightening torque specs
| Tightening torque specs | |
| Spark plug | 12 Nm; 1.2 kg·m; 8.6 ft·lb |
| Connecting rod bolt | 6 Nm; 0.6 kg·m; 4.3 ft·lb |
| Crankcase cover bolt | 7.5 Nm; 0.75 kg·m; 5.4 ft·lb |
| Oil case bolt | 7.5 Nm; 0.75 kg·m; 5.4 ft·lb |
| Valve cover bolt | 6 Nm; 0.6 kg·m; 4.3 ft·lb |
| Oil drain bolt | 11 Nm; 1.1 kg·m; 8 ft·lb |
| Flywheel nut | 21 Nm; 2.1 kg·m; 15 ft·lb |
| Fuel tank bolt | 10 Nm; 1.0 kg·m; 7 ft·lb |
| Igniton coil bolt | 6 Nm; 0.6 kg·m; 4.3 ft·lb |
| Fan caver stud bolt | 6 Nm; 0.6 kg·m; 4.3 ft·lb |
| Governor arm nut | 7 Nm; 0.7 kg·m; 5.1 ft·lb |
| Carburetor drain bolt | 4.5 Nm; 0.45 kg·m; 3.3 ft·lb |
| Others | |
| 4 mm bolts, nuts | 3.5 Nm; 0.35 kg·m; 2.5 ft·lb |
| 5 mm bolts, nuts | 5.5 Nm; 0.55 kg·m; 4.0 ft·lb |
| 6 mm bolts, nuts | 10 Nm; 1.0 kg·m; 7 ft·lb |
Service Information
| Engine | |
| Maximum speed | 4,800 ± 150 rpm |
| Idle speed | 2,500 ± 200 rpm |
| Cylinder compression | 4.3 kg/cm2 (61.2 psi) at 1000 rpm |
| Valve clearance | |
| Intake valve | 0.06-0.10 mm (0.0024-0.0039 in) |
| Exhaust valve | 0.09-0.13 mm (0.0035-0.0051 in) |
| Oil system | |
| Oil type | Honda 4-stroke or an equivalent (SE or SF) |
| Recommended oil | SAE 10W-30 |
| Oil capacity | 0.25 liters (0.26 US.qts, 0.22 Imp. qts) |
| Ignition system | |
| Ignition timing | 30° B.T.D.C. |
| Spark plug | NGK: CR5HSB DENSO: U16FSR-UB |
| Spark plug gap | 0.6-0.7 mm (0.024-0.028 in) |
| Spark plug tightening torque | 12 Nm; 1.2 kg·m; 8.6 ft·lb |
| Primary ignition coil resistance | 0.98-1.20 Ω |
| Secondary ignition coil resistance | 8-10 kΩ |
| Ignition coil air gap | 0.3-0.5 mm (0.012-0.020 in) |
| Carburetor | |
| Main jet | #55 |
| Float height | 12 mm (0.47 in) |
| Pilot screw opening | 1-1/8 turns out |
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