Honda GXV120

Honda GXV120The Honda GXV120 is a 118 cc, (7.2 cu·in) natural aspirated single-cylinder four-stroke air-cooled internal combustion gasoline engine with a vertical shaft, manufactured by Honda Motor Company for general-purpose applications.

A 60.0 mm (2.36 in) cylinder bore and 42.0 mm (1.65 in) piston stroke give the GXV120 engine a total of 118 cc of displacement. The compression ratio rating are 8.7:1 or 8.0:1.

The Honda GXV120 engine produced 4.0 PS (2.9 kW; 4.0 HP) at 3,600 rpm of maximum output power and 8.0 N·m (0.8 kg·m, 5.9 ft·lb) at 2,700 rpm of peak torque.

The Honda GXV120 features:

  • OHV design
  • Transistorized magneto ignition system
  • Horizontal type carburetor with butterfly valve
  • Centrifugal governor
  • Splash lubrication system
  • Forced air cooling system
  • Recoil starter

General information

Engine Specifications
Engine model GXV120
Engine type 4-stroke, OHV, single-cylinder
Displacement 118 cm3, (7.2 cu·in)
Max. horsepower 4.0 PS (2.9 kW; 4.0 HP) at 3,600 rpm
Max. torque 8.0 N·m (0.8 kg·m, 5.9 ft·lb) at 2,700 rpm
Cooling system Forced air
Air cleaner Dual-element type
Lubricating system Splash
Ignition system Transistorized magneto ignition
Fuel system Horizontal type carburetor with butterfly valve
Fuel consumption 250 g/HPh
Fuel tank capacity 1.0 L (0.26 US. gal. 0.22 Imp. gal.)
Fuel used Unleaded gasoline (octane number 86 or higher)
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)
Dry weight

Cylinder Block and Head

Cylinder block
Compression ratio: 8.7:1 for engine with S/N: 100001-1219523
8.0:1 for engine with S/N: from 1219524
Cylinder bore: 60.0 mm (2.36 in)
Piston stroke: 42.0 mm (1.65 in)
Cylinder internal diameter (standard): 60.000 mm (2.3622 in)
Piston skirt outer diameter (standard): 59.985 mm (2.3616 in)
Number of piston rings (compression / oil): 2/1
Connecting rod big end diameter (standard): 26.020 mm (1.0244 in)
Connecting rod small end diameter (standard): 13.005 mm (0.512 in)
Piston pin diameter: 13.000 mm (0.5118 in)
Side clearance (Top): 0.015-0.045 mm (0.0006-0.0018 in)
Side clearance (Second): 0.015-0.045 mm (0.0006-0.0018 in)
Ring end gap (Top): 0.200-0.400 mm (0.0079-0.0157 in)
Ring end gap (Second): 0.200-0.400 mm (0.0079-0.0157 in)
Ring end gap (Oil): 0.150-0.350 mm (0.0059-0.0138 in)
Ring width (Top): 1.500 mm (0.0591 in)
Ring width (Second): 1.500 mm (0.0591 in)
Ring width (Oil): 2.500 mm (0.0984 in)
Crankpin journal diameter: 25.980 mm (1.0228 in)
Cylinder head
Valve arrangement: OHV, gear driven
Valves: 2
Valve steam diameter (INTAKE): 5.480 mm (0.2157 in)
Valve steam diameter (EXHAUST): 5.440 mm (0.2142 in)
Valve spring free length (INTAKE): 34.000 mm (1.3386 in)
Valve spring free length (EXHAUST): 34.000 mm (1.3386 in)
Camshaft lobe height (INTAKE): 27.700 mm (1.0905 in)
Camshaft lobe height (EXHAUST): 27.750 mm (1.0925 in)
Camshaft journal diameter : 13.984 mm (0.5506 in)

Tightening torque specs

Tightening torque specs
Connecting rod lower cap 12 Nm; 1.2 kg·m; 9 ft·lb
Cylinder head bolt 24 Nm; 2.4 kg·m; 17 ft·lb
Flywheel nut 75 Nm; 7.5 kg·m; 54 ft·lb
Pivot adjusting nut 10 Nm; 1.0 kg·m; 7 ft·lb
Pivot bolt 24 Nm; 2.4 kg·m; 17 ft·lb
Oil filter extension 10 Nm; 1.0 kg·m; 7 ft·lb
Oil drain bolt 18 Nm; 1.8 kg·m; 13 ft·lb
Oil pan 24 Nm; 2.4 kg·m; 17 ft·lb
Standard torque values
Bolt, nut (5 mm) 5.5 Nm; 0.55 kg·m; 4.0 ft·lb
Bolt, nut (6 mm) 10 Nm; 1.0 kg·m; 7 ft·lb
Bolt, nut (8 mm) 24 Nm; 2.4 kg·m; 17 ft·lb
Bolt, nut (10 mm) 37.5 Nm; 3.75 kg·m; 27 ft·lb
Bolt, nut (12 mm) 55 Nm; 5.5 kg·m; 40 ft·lb

Service Data

Engine
Maximum speed: 3,100 ± 100 rpm
Idle speed: 2,000 ± 150 rpm
Cylinder compression: 3.0-7.0 kg/cm2 (44-100 psi) at 600 rpm
Valve clearance
Intake valve clearance: 0.14-0.16 mm (0.0055-0.0063 in)
Exhaust valve clearance: 0.19-0.21 mm (0.0075-0.0083 in)
Oil system
Lubrication system: Splash
Oil type: Honda 4-stroke or an equivalent (SE or SF)
Recommended oil: SAE 10W-30
Oil capacity: 0.6 L (0.63 US. qt, 0.53 Imp. qt.)
Fuel system
Type: Horizontal type carburetor with butterfly valve
Main jet: #65
Float height: 12.2-15.2 mm (0.48-0.60 in)
Pilot screw opening: 3 turns out
Ignition system
Type: Transistorized magneto ignition
Ignition timing: 25° B.T.D.C.
Spark plug: NGK: BP5ES, BPR5ES NIPPONDENSO: W16EP-U, W16EPR-U
Spark plug gap: 0.7-0.8 mm (0.0276-0.0315 in)

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