Honda GD321

Honda GD321The Honda GD321 is a (317 cc, 19.34 cu-in) single-cylinder air-cooled 4-stroke internal combustion diesel engine with horizontal shaft, manufactured by Honda Motor Company for general-purpose applications.

This engine has a single-cylinder; overhead valves and direct injection combustion system. The motor used Zexel PFRIKX fuel injection pump and Zexel DLLA-P injection nozzle. The GD321 engine could be equipped with recoil starter and starter motor, or recoil starter only.

The GD321 has a 76.0 mm (2.99 in) cylinder bore and 70.0 mm (2.76 in) piston stroke. The compression ratio is 20:1 for North America type and 19:1 for other engines. It produced 7.0 HP (5.2 kW) of maximum output and 15.7 N·m (1.6 kg·m, 11.57 ft·lb) at 2,500 rpm of torque.

General information

Engine Specifications
Type4-stroke, OHV, single cylinder
Displacement317 cm 3 (19.34 cu-in)
Max. horsepower S,Q,W,V,P type: 7.0 HP (5.2 kW) at 3,600 rpm
B type: 6.0 HP (4.4 kW) at 3,000 rpm
L type: 6.8 HP (5.0 kW) at 1,800 rpm
Max. torque (crank PTO) S,Q,W,V,P type:15.7 N·m (1.6 kg·m, 11.57 ft·lb) at 2,500 rpm
B type: 15.7 N·m (1.6 kg·m, 11.57 ft·lb) at 1,800 rpm
L type: 30.4 N·m (3.1 kg·m, 23 ft·lb) at 1,250 rpm
Cooling systemForced-air
Lubricating systemForced spray
Starting systemRecoil starter or starter motor
Stoping systemFuel cut with speed control lower (Stop lever)
Fuel usedDiesel fuel
Fuel tank capacity4.6 l (1.21 US. Gal, 1.2 Imp. Gal.)
Fuel consumption S,Q,W,V,P type: 180 g/HPh
B type: 196 g/HPh
PTO shaft rotationCounterclockwise (from PTO shaft side)

Cylinder Block and Head

Cylinder block
Compression ratio:19:1, 20:1
Bore x Stroke76 mm X 70 mm (2.99 x 2.76 in)
Sleeve internal diameter76.000-76.017 mm (2.9921-2.9928 in)
Piston skirt outer diameter75.940-75.960 mm (2.9898-2.9905 in)
Number of piston rings (compression / oil):2 / 1
Ring side clearanceTop0.065-0.095 mm (0.0026-0.0037 in)
Second0.055-0.085 mm (0.0022-0.0033 in)
Oil0.020-0.055 mm (0.0008-0.0022 in)
Ring end gapTop0.20-0.35 mm (0.008-0.014 in)
Second0.20-0.35 mm (0.008-0.014 in)
Oil0.20-0.40 mm (0.008-0.016 in)
Ring widthTop1.990-1.975 mm (0.0783-0.0778 in)
Second1.990-1.975 mm (0.0783-0.0778 in)
Oil3.990-3.970 mm (0.1571-0.01563 in)
Connecting rod small end ID20.010-20.028 mm (0.7878-0.7885 in)
Connecting rod big end ID41.000-41.024 mm (1.6142-1.6151 in)
Crankpin outer diameter37.976-38.000 mm (1.4951-1.4961 in)
Main journal outer diameter46.970-46.994 mm (1.8492-1.8502 in)
Cylinder Head
Distortion of cylinder head0.05 mm (0.002 in)
Valve Arrangement:OHV
Stem outer diameter (standard):INTAKE6.590-6.575 mm (0.2594-0.2589 in)
EXHAUST6.550-6.540 mm (0.2579-0.2575 in)
Guide internal diameterINTAKE / EXHAUST6.600-6.615 mm (0.2598-0.2604 in)
Spring free length33.7 mm (1.33 in)
Cam lobe heightINTAKE / EXHAUST41.022 mm (1.6150 in)
Valve rocker arm internal diameterINTAKE / EXHAUST16.000-16.018 mm (0.6300-0.6306 in)
Rocker arm shaft outer diameterINTAKE / EXHAUST15.984-15.966 mm (0.6293-0.6286 in)

Tightening torque specs

Tightening torque specs
Cylinder head bolts43 Nm; 4.3 kg·m; 31 ft·lb
Cylinder head nuts11 Nm; 1.1 kg·m; 8 ft·lb
Rocker arm shaft nuts11 Nm; 1.1 kg·m; 8 ft·lb
Tappet adjusting nuts9 Nm; 0.9 kg·m; 6.5 ft·lb
Oil pan bolt bolts M11: 71 Nm; 7.1 kg·m; 51 ft·lb
M8: 22 Nm; 2.2 kg·m; 16 ft·lb
Connecting rod cap nuts32 Nm; 3.2 kg·m; 23 ft·lb
Relief valve33 Nm; 3.3 kg·m; 24 ft·lb
Drain plug bolt33 Nm; 3.3 kg·m; 24 ft·lb
Flywheel nut250 Nm; 25.0 kg·m; 180 ft·lb
Injection nozzle10 Nm; 1.0 kg·m; 7 ft·lb
Air breather joint nuts18 Nm; 1.8 kg·m; 13 ft·lb
Fuel injection pump bolts22 Nm; 2.2 kg·m; 16 ft·lb
Fuel joint bolts28 Nm; 2.8 kg·m; 20 ft·lb
Air breather bolt18 Nm; 1.8 kg·m; 13 ft·lb
Fuel pipe nuts20 Nm; 2.0 kg·m; 14 ft·lb
Muffler nuts, bolts22 Nm; 2.2 kg·m; 16 ft·lb
Fuel tank bolts11 Nm; 1.1 kg·m; 18 ft·lb
Fuel filter bolts11 Nm; 1.1 kg·m; 18 ft·lb
Drain bolt11 Nm; 1.1 kg·m; 18 ft·lb
5 mm bolts, nuts5.0 Nm; 0.50 kg·m; 4.0 ft·lb
6 mm bolts, nuts10 Nm; 1.0 kg·m; 7 ft·lb
8 mm bolts, nuts21 Nm; 2.1 kg·m; 15 ft·lb
10 mm bolts, nuts35 Nm; 3.5 kg·m; 25 ft·lb
12 mm bolts, nuts60 Nm; 6.0 kg·m; 44 ft·lb

Service Information

Maximum speed3,750 ± 150 rpm
Idle speed1,400 ± 150 rpm
Cylinder compression26.0 kg/cm2 (370 psi) at 300 rpm
Valve clearance
Intake valve0.15 ± 0.02 (0.006 ± 0.00078)
Exhaust valve0.15 ± 0.02 (0.006 ± 0.00078)
Oil system
Oil typeDiesel oil (API Service Classification CC or CD)
Recommended oilSAE 10W-30
Oil capacity1.15 l (1.21 US. qt, 1.01 Imp. qt.)
Oil pressure3.9-5.2 kg/cm2 (55.5-74.0 psi) at 3,600 rpm
Resistance2.0 ±0.5 Ω
Starter motor
Brush length10 mm (0.39 in)
Mica depth0.4-0.5 mm (0.016-0.020 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.

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