Honda GXH50

Honda GXH50The Honda GXH50 is a 49 cc (3.0 cu·in) natural aspirated single-cylinder four-stroke air-cooled internal combustion gasoline engine with a horizontal shaft, manufactured by Honda Motor Company for general-purpose applications.

It has an 41.8 mm (1.65 in) cylinder bore and 36.0 mm (1.42 in) piston stroke. The compression ratio rating is 8.0:1.

The GXH50 engine produced 2.4 PS (1.8 kW; 2.4 HP) at 7,000 rpm of maximum horsepower and 3.04 N·m (0.3 kg·m, 2.2 ft·lb) at 4,500 rpm of maximum torque.

The Honda GXH50 features:

  • OHV design
  • Transistorized magneto ignition system
  • Float type carburetor
  • Centrifugal governor
  • Splash lubrication system
  • Forced air cooling system
  • Recoil starter

General information

Engine Specifications
Engine model GXH50
Engine type 4-stroke, OHV, single-cylinder
Displacement 49 cm3, (3.0 cu·in)
Max. horsepower 2.4 PS (1.8 kW; 2.4 HP) at 7,000 rpm
Max. torque 3.04 N·m (0.3 kg·m, 2.2 ft·lb) at 4,500 rpm
Cooling system Forced air
Air cleaner Semi-dry type
Lubricating system Splash
Ignition system Transistorized magneto ignition
Fuel system Float type carburetor
Fuel consumption 240 g/HPh
Fuel tank capacity 0.77 L (0.2 US. gal. 0.17 Imp. gal.)
1.2 L (0.32 US. gal, 0.26 Imp. gal.)
Starting system Recoil starter
Stoping system Ignition primary circuit ground
Governor Centrifugal governor
PTO shaft rotation Counterclockwise (from PTO shaft side)
Dimensions (L x W X H) 225 x 274 x 353 mm (8.9 x 10.8 x 13.9 in)
Dry weight 5.5 kg (12.1 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio: 8.0:1
Cylinder bore: 41.8 mm (1.65 in)
Piston stroke: 36.0 mm (1.42 in)
Cylinder internal diameter (standard): 41.800-41.815 mm (1.6457-1.6463 in)
Piston skirt outer diameter (standard): 41.770-41.790 mm (1.6445-1.6453 in)
Number of piston rings (compression / oil): 2/1
Connecting rod small end diameter (standard): 10.006-10.007 mm (0.3939-0.394 in)
Connecting rod center distance: 15.000-15.011 mm (0.5906-0.591 in)
Side clearance (Top): 0.015-0.050 mm (0.0006-0.002 in)
Side clearance (Second): 0.015-0.050 mm (0.0006-0.002 in)
Ring end gap (Top): 0.150-0.300 mm (0.0059-0.0118 in)
Ring end gap (Second): 0.150-0.300 mm (0.0059-0.0118 in)
Ring width (Top): 0.770-0.790 mm (0.0303-0.0311 in)
Ring width (Second): 0.970-0.990 mm (0.0382-0.039 in)
Crankpin journal diameter: 14.973-14.984 mm (0.5895-0.5899 in)
Cylinder head
Valve arrangement: OHV, gear driven
Valves: 2
Valve steam diameter (INTAKE): 3.970-3.985 mm (0.1563-0.1569 in)
Valve steam diameter (EXHAUST): 3.935-3.950 mm (0.1549-0.1555 in)
Valve spring free length (INTAKE): 23.7 mm (0.9331 in)
Valve spring free length (EXHAUST): 23.7 mm (0.9331 in)
Camshaft lobe height (INTAKE): 27.972 mm (1.1013 in)
Camshaft lobe height (EXHAUST): 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 Data

Engine
Maximum speed: 7,800 ± 150 rpm
Idle speed: 2,500 ± 20 rpm
Cylinder compression: 4.3 kg/cm2 (61 psi) at 1,000 rpm
Valve clearance
Intake valve clearance: 0.06-0.10 mm (0.0024-0.0039 in)
Exhaust valve clearance: 0.09-0.13 mm (0.0035-0.0051 in)
Oil system
Lubrication system: Splash
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.)
Fuel system
Type: Float type carburetor
Main jet: #55
Float height: 12.0 mm (0.4724 in)
Pilot screw opening: 1-1/8 turns out
Ignition system
Type: Transistorized magneto ignition
Ignition timing: 30° B.T.D.C.
Spark plug: NGK: CR5HSB DENSO: U16FSR-UB
Spark plug gap: 0.6-0.7 mm (0.0236-0.0276 in)
Spark plug torque: 12 N·m (1.2 kg·m, 8.8 ft·lb)
Ignition coil air gap 0.3-0.5 mm (0.0118-0.0197 in)
ATTENTION! Dear visitors, this is an informational database of technical specifications, we are not a parts supplier or a marketplace.

We try to use official documentation and verify the published data, but errors may occur. In addition, specifications of machinery and equipment may vary depending on markets and modifications. We do not recommend the use of this data for spare parts or repairs. Use official service manuals or parts catalogs for your product.

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