The Honda GXH50 is a small (49 cc, 2.99 cu-in) single-cylinder air-cooled 4-stroke internal combustion gasoline engine with horizontal shaft, manufactured by Honda Motor Company, for general-purpose applications, such as construction and industrial equipment; agricultural equipment; water pumps.
This engine has a single-cylinder, overhead-valve, and precision camshaft design; high compression ratio for better fuel efficiency; ball bearing supported crankshaft for greater stability; large capacity, multi-chamber exhaust system. The Honda GXH50 engine is equipped with transistorized magneto ignition, float type carburetor and recoil starter.
The GXH50 motor a compression ratio rating is 8.0:1, cylinder bore and piston stroke are 41.8 mm (1.65 in) and 36.0 mm (1.42 in), respectively. The Honda GXH50 engine produces 2.5 PS (1.8 kW) at 7,000 rpm and 3.04 N·m (0.31 kg·m, 2.25 ft·lb) at 4,500 rpm of torque.
General information
| Engine Specifications | |
| Model | GXH50 |
| Type | 4-stroke, OHV, single cylinder |
| Displacement | 49 cm 3 (2.99 cu-in) |
| Max. horsepower | Net: 2.1 HP (1.6 kW) at 7,000 rpm Gross: 2.5 PS (1.8 kW) at 7,000 rpm |
| Max. torque (crank PTO) | Net: 2.7 N·m (0.27 kg·m, 2.0 ft·lb) at 4,500 rpm Gross: 3.04 N·m (0.31 kg·m, 2.25 ft·lb) at 4,500 rpm |
| Carburetor | Float type |
| Cooling system | Forced-air |
| Ignition system | Transistorized magneto ignition |
| Lubricating system | Splash |
| Starting system | Recoil starter |
| Stoping system | Ignition primary circuit ground |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Fuel tank capacity | 1.2 L (0.32 US gal, 0.26 Imp gal) |
| Fuel consumption | 240 g/HPh |
| PTO shaft rotation | Counterclockwise (from PTO shaft side) |
Cylinder Block and Head
| Cylinder block | ||
| Compression ratio: | 8.0:1 | |
| Bore x Stroke | 41.8 mm X 36 mm (1.65 x 1.42 in) | |
| Sleeve internal diameter | 41.800-41.815 mm (1.6445-1.6463 in) | |
| Piston skirt outer diameter | 41.770-41.790 mm (1.6445-1.6453 in) | |
| Ring side clearance | Top/second | 0.015-0.050 mm (0.0006-0.0020 in) |
| Ring end gap | Top | 0.15-0.30 mm (0.0059-0.0118 in) |
| Second | 0.15-0.30 mm (0.0059-0.0118 in) | |
| Ring width | Top | 0.77-0.79 mm (0.030-0.031 in) |
| Second | 0.97-0.99 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 | |
| Stem outer diameter (standard): | INTAKE | 3.970-3.985 mm (0.1563-0.1569 in) |
| 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 |
| Flywheel nut | 22 Nm; 2.2 kg·m; 16 ft·lb |
| Igniton coil bolt | 6 Nm; 0.6 kg·m; 5 ft·lb |
| Carburetor drain screw | 1.2 Nm; 0.12 kg·m; 0.9 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 | 7,800 ± 150 rpm |
| Idle speed | 2,500 ± 200 rpm |
| Cylinder compression | 4.3 kg/cm2 (61 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 l (0.26 US. qt, 0.22 Imp. qt.) |
| 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 kΩ |
| 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 |
Author:
Please …What size are the 4 bolts around the shaft that attaches a transmission on a Honda GXH 50? I have searched my manual and websites with no luck. Thx