Honda GX660

Honda GX660The Honda GX660 is a 688 cc (42.0 cu·in) natural aspirated two-cylinders four-stroke air-cooled internal combustion small gasoline engine with a horizontal shaft, manufactured by Honda Motor Company for general-purpose applications.

It has a 78.0 mm (3.07 in) cylinder bore and 72.0 mm (2.83 in) piston stroke. The compression ratio rating is 9.3:1.

The GX660 engine produced 21.8 PS (16.0 kW; 21.5 HP) at 3,600 rpm of maximum horsepower, 17.0 PS (12.5 kW; 16.8 HP) at 3,600 rpm of continuous rated power, and 48.3 N·m (4.9 kg·m, 35.6 ft·lb) at 2,500 rpm of maximum torque.

The Honda GX660 features:

  • Overhead valve (OHV) design
  • C.D.I. (Capacitor Discharge Ignition)
  • Two barrel horizontal type carburetor with butterfly valve
  • Centrifugal governor
  • Forced feed lubrication system
  • Forced air cooling system
  • Starter motor

General information

Engine Specifications
Engine modelGX660
Engine type4-stroke, OHV, two-cylinders
Displacement688 cm3, (42.0 cu·in)
Max. horsepower21.8 PS (16.0 kW; 21.5 HP) at 3,600 rpm
Max. torque48.3 N·m (4.9 kg·m, 35.6 ft·lb) at 2,500 rpm
Cooling systemForced air
Air cleanerDual type
Lubricating systemForced feed
Ignition systemC.D.I. (Capacitor Discharge Ignition) type magneto
Fuel system2 barrel horizontal type carburetor with butterfly valve
Fuel consumption6.3 Liters (1.66 US gal, 1.39 Imp gal) / h
Fuel usedUnleaded gasoline (octane number 86 or higher)
Starting systemStarter motor
Stoping systemIgnition primary circuit open
GovernorCentrifugal governor
PTO shaft rotationCounterclockwise (from PTO shaft side)
Dimensions (L x W X H)405 x 410 x 438 mm (15.9 x 16.1 x 17.2 in)
Dry weight44.0 kg (97 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio:9.3:1
Cylinder bore:78.0 mm (3.07 in)
Piston stroke:72.0 mm (2.83 in)
Cylinder internal diameter (standard):78.000-78.015 mm (3.0709-3.0715 in)
Piston skirt outer diameter (standard):77.985-77.995 mm (3.0703-3.0707 in)
Number of piston rings (compression / oil):2/1
Connecting rod big end diameter (standard):44.988-45.012 mm (1.7712-1.7721 in)
Connecting rod small end diameter (standard):18.006-18.018 mm (0.7089-0.7094 in)
Piston pin diameter:17.994-18.000 mm (0.7084-0.7087 in)
Side clearance (Top):0.050-0.080 mm (0.002-0.0031 in)
Side clearance (Second):0.050-0.080 mm (0.002-0.0031 in)
Ring end gap (Top):0.200-0.350 mm (0.0079-0.0138 in)
Ring end gap (Second):0.200-0.350 mm (0.0079-0.0138 in)
Ring end gap (Oil):0.200-0.700 mm (0.0079-0.0276 in)
Ring width (Top):1.140-1.155 mm (0.0449-0.0455 in)
Ring width (Second):1.140-1.155 mm (0.0449-0.0455 in)
Crankshaft main journal diameter:39.984-40.000 mm (1.5742-1.5748 in)
Crankpin journal diameter:44.973-44.983 mm (1.7706-1.771 in)
Crankshaft center distance:36 mm (1.415 in)
Cylinder head
Valve arrangement:OHV, gear driven
Valves:2,(4 valves in total)
Valve steam diameter (INTAKE):5.475-5.490 mm (0.2156-0.2161 in)
Valve steam diameter (EXHAUST):5.435-5.450 mm (0.214-0.2146 in)
Valve spring free length (INTAKE):38.3 mm (1.5079 in)
Valve spring free length (EXHAUST):38.3 mm (1.5079 in)
Camshaft lobe height (INTAKE):29.506-29.706 mm (1.1617-1.1695 in)
Camshaft lobe height (EXHAUST):29.410-29.610 mm (1.1579-1.1657 in)
Camshaft journal diameter :16.982-17.000 mm (0.6686-0.6693 in)

Tightening torque specs

Tightening torque specs
Connecting rod bolt22 Nm; 2.2 kg·m; 16 ft·lb
Cylinder nut37 Nm; 3.8 kg·m; 27 ft·lb
Oil drain plug bolt45 Nm; 4.5 kg·m; 33 ft·lb
Flywheel nut235 Nm; 24.0 kg·m; 173 ft·lb
Oil filter cartridge12 Nm; 1.2 kg·m; 9 ft·lb
Tappet adjusting nut7.5 Nm; 0.75 kg·m; 5.5 ft·lb
Governor arm nut11 Nm; 1.1 kg·m; 8 ft·lb
Fuel pump cover screw4 Nm; 0.4 kg·m; 3 ft·lb
Oil pressure switch9 Nm; 0.9 kg·m; 6.6 ft·lb

Service Data

Maximum speed: GX660/GX660R: 3,600-4,000 rpm
GX660R(VXE1): 3,050-3,350 rpm
Cylinder compression:0.5-0.7 MPa (5.09-7.14 kgf/cm2 , 73-102 psi) / 500 rpm
Valve clearance
Intake valve clearance:0.08±0.02 mm (0.003±0.001 in)
Exhaust valve clearance:0.10±0.02 mm (0.004±0.001 in)
Oil system
Lubrication system:Forced feed
Oil type:API SE or later
Recommended oil:SAE 10W-30
Oil capacity: Without oil filter replacement: 1.5 L (1.59 US. qt, 1.32 Imp. qt.)
With oil filter replacement: 1.7 L (1.80 US. qt, 1.50 Imp. qt.)
Fuel system
Type:2 barrel horizontal type carburetor with butterfly valve
Main jet:No.1 / No.2 cylinder: #112
Float height:15.5 mm (0.6102 in)
Pilot screw opening: No.1 cylinder: 1-3/4 turns out
No.2 cylinder: 1-7/8 turns out
Ignition system
Type:C.D.I. (Capacitor Discharge Ignition) type magneto
Ignition timing:B.T.D.C. 9°
Spark plug:NGK: ZFR5F
Spark plug gap:0.7-0.8 mm (0.0276-0.0315 in)
Ignition coil air gap0.2-0.6 mm (0.0079-0.0236 in)
Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

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.

Be the first to comment

Leave a Reply

Your email address will not be published.