The Honda GXV630 is a 688 cc (41.97 cu-in) V-twin cylinder air-cooled four-stroke internal combustion small gasoline engine with vertical shaft manufactured by Honda Motor Company for general-purpose applications, such as riding mowers and lawn tractors, construction equipment and other professional heavy-duty applications.
The Honda GXV630 engine has an OHV (overhead valve) design with 90° V-twin cylinders; horizontal type, two-barrel inner-vent carburetor with butterfly valve; digital C.D.I.(Capacitor Discharge Ignition) ignition system with variable timing and electric starter.
The GXV630 motor uses a hemispherical combustion chamber design. It offers a higher 9.3:1 compression ratio, higher power output and greater displacement in a more compact design. The cylinder bore is 78.0 mm (3.07 in) and the piston stroke is 72.0 mm (2.83 in). The GXV630 engine produces 21.1 PS (15.5 kW; 20.8 HP) of maximum horsepower at 3,600 rpm; 16.3 PS (12.0 kW; 16.0 HP) of continuous rated power at 3,600 rpm., and 48.3 N·m (4.93 kg·m, 35.6 ft·lb) of torque at 2,500 rpm.
General information
| Engine Specifications | |
| Model | GXV630 / GXV630R |
| Type | 4-stroke, OHV, 90° V-twin |
| Displacement | 688 cm 3 (41.97 cu-in) |
| Max. horsepower | 21.1 PS (15.5 kW; 20.8 HP) at 3,600 rpm |
| Max. torque (crank PTO) | 48.3 N·m (4.93 kg·m, 35.6 ft·lb) at 2,500 rpm |
| Carburetor | Horizontal type, two barrel, inner-vent, butterfly valve |
| Cooling system | Forced-air |
| Ignition system | Digital C.D.I. with variable timing |
| Lubricating system | Forced feed |
| Starting system | Electric starter |
| Stoping system | Ignition primary circuit open |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Fuel consumption | 4.7 L (1.24 US gal, 1.03 Imp gal) / h |
| PTO shaft rotation | Counterclockwise (from PTO shaft side) |
Dimensions and Weight
| GXV630 | |
| Length, mm (in) | 449 (17.7) |
| Width, mm (in) | 420 (16.5) |
| Height, mm (in) | 475 (18.7) |
| Dry weight, kg (lb) | 46.5 (102.5) |
Cylinder Block and Head
The Honda GXV630 engine uses integrated cylinder and head, cast iron sleeve, a hemispherical combustion chamber, aluminum push rods with steel tips, racing inspired forged steel connecting rods and forged steel crankshaft with pressure fed crankshaft bearings,
| Cylinder block | ||
| Compression ratio: | 9.3:1 | |
| Bore x Stroke | 78 X 72 mm (3.07 x 2.83 in) | |
| Sleeve internal diameter | 78.000-78.015 mm (3.0709-3.0715 in) | |
| Piston skirt outer diameter | 77.985-77.995 mm (3.0703-3.0707 in) | |
| Ring side clearance | Top/Second | 0.050-0.080 mm (0.0020-0.0031 in) |
| Ring end gap | Top/Second | 0.20-0.35 mm (0.008-0.0138 in) |
| Oil (side rail | 0.20-0.70 mm (0.008-0.028 in) | |
| Ring width | Top/Second | 1.140-1.155 mm (0.0449-0.0455 in) |
| Connecting rod small end ID | 18.006-18.018 mm (0.7089-0.7094 in) | |
| Piston pin outer diameter | 17.994-18.000 mm (0.7084-0.7087 in) | |
| Crankpin diameter | 44.973-44.983 mm (1.7706-1.7710 in) | |
| Crankshaft journal diameter | 39.984-40.000 mm (1.5742-1.5748 in) | |
| Cylinder Head | ||
| Warpage (limit) | 0.10 mm (0.004 in) | |
| Valve Arrangement: | OHV | |
| Valves: | 4 (2 per cylinder) | |
| Stem outer diameter (standard): | INTAKE | 5.475-5.490 mm (0.2156-0.2161 in) |
| EXHAUST | 5.435-5.450 mm (0.2140-0.2146 in) | |
| Valve spring free length: | 38.3 mm (1.51 in) | |
| Valve lifter internal diameter: | 6.010-6.040 mm (0.2366-0.2378 in) | |
| Valve lifter shaft outer diameter: | 5.970-6.000 mm (0.2350-0.2362 in) | |
| Camshaft journal diameter: | 16.982-17.000 mm (0.6686-0.6693 in) | |
| Cam height: | INTAKE | 29.506-29.706 mm (1.1617-1.1695 in) |
| EXHAUST | 29.410-29.610 mm (1.1579-1.1657 in) | |
Tightening torque specs
| Tightening torque specs | |
| Connecting rod bolt | 22 Nm; 2.2 kg·m; 16 ft·lb |
| Cylinder nut | 37 Nm; 3.8 kg·m; 27 ft·lb |
| Oil drain plug bolt | 45 Nm; 4.5 kg·m; 33 ft·lb |
| Flywheel nut | 235 Nm; 24.0 kg·m; 173 ft·lb |
| Oil filter cartridge | 12 Nm; 1.2 kg·m; 9 ft·lb |
| Tappet adjusting nut | 7.5 Nm; 0.75 kg·m; 5.5 ft·lb |
| Governor arm nut | 11 Nm; 1.1 kg·m; 8 ft·lb |
| Fuel pump cover screw | 4 Nm; 0.4 kg·m; 3 ft·lb |
| Oil pressure switch | 9 Nm; 0.9 kg·m; 6.6 ft·lb |
Service Information
| Engine | |
| Maximum speed | 3,400 ± 150 rpm |
| Idle speed | 1,400 ± 150 rpm |
| Cylinder compression | 5.0-7.0 kg/cm2 (73-102 psi) at 500 rpm |
| Valve clearance | |
| Intake valve clearance | 0.08±0.02 mm |
| Exhaust valve clearance | 0.10±0.02 mm |
| Oil system | |
| Oil type | Honda 4-stroke or an equivalent (SE or later) |
| Recommended oil | SAE 10W-30 |
| Oil capacity |
Without oil filter: 1.7 Liters (1.80 US qt, 1.50 Imp qt) With oil filter: 1.9 Liters (2.01 US qt, 1.67 Imp qt) |
| Oil change interval | Every 6 month or 100 Hrs. |
| Carburetor | |
| Main jet |
Cylinder №1: #105 Cylinder №2: #110 |
| Float height | 15.5 mm (0.61 in) |
| Pilot screw opening |
Cylinder №1: 2 turns out Cylinder №2: 2-1/8 turns out |
| Ignition system | |
| Ignition timing | 9°-23° B.T.D.C. |
| Spark plug | NGK: ZFR5F |
| Spark plug gap | 0.7-0.8 mm (0.028-0.031 in) |
| Ignition coil air gap | 0.4 ± 0.2 (0.016 ± 0.008) |
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