Honda GXV50

Honda GXV50 engineThe Honda GXV50 is a small (49 cc, 2.99 cu-in) single-cylinder air-cooled 4-stroke internal combustion gasoline engine with vertical shaft, manufactured by Honda Motor Company.

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 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 1.8 kW (2.5 HP) at 7,000 rpm and 3.04 N·m (0.31 kg·m, 2.25 ft·lb) of torque at 4,500 rpm.

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 HP (1.8 kW) at 7,000 rpm
Max. torque (crank PTO) 3.04 N·m (0.31 kg·m, 2.25 ft·lb) 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 l (0.53 US. Gal, 0.44 Imp. Gal.)
Fuel consumption 250 g/HPh
PTO shaft rotation Counterclockwise (from PTO shaft side)

Dimensions and Weight

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)
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 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)
Ring side clearance Top/second 0.015-0.050 mm (0.0006-0.0020 in)
Ring end gap Top/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
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
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

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 l (0.26 US. qt, 0.22 Imp. qt.)
Ignition system
Ignition timing 30° B.T.D.C.
Spark plug NGK: CR5HSB
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)
Main jet #55
Float height 12 mm (0.47 in)
Pilot screw opening 1-1/8 turns out
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