Honda GD320

Honda GD320 engineThe Honda GD320 is a 317 cc (19.34 cu-in) single-cylinder, air-cooled, four-stroke internal combustion diesel engine with horizontal shaft, manufactured by Honda Motor Company for general-purpose applications since 1988.

This engine has a single cylinder and overhead valves. The GD320 engine has a recoil starter or starter motor.

A 76.0 mm (2.99 in) cylinder bore and 70.0 mm (2.76 in) piston stroke give the engine a total of 317 cc (14.4 cu-in) of displacement. Compression ratio rating is 19.0:1.

The Honda GD320 produced 7.1 PS (5.2 KW; 7.0 HP) at 3,600 rpm of maximum output power and 6.0 HP (4.4 kW) of continuous output. The peak torque is 15.7 Nm (1.6 kg·m; 11.6 lbf·ft) at 2,500 rpm.

General information

Engine Specifications
Type4-stroke, OHV, single cylinder
Displacement317 cm 3 (19.34 cu-in)
Max. horsepower7.1 PS (5.2 KW; 7.0 HP) at 3,600 rpm
Max. torque (crank PTO)15.7 Nm (1.6 kg·m; 11.6 lbf·ft) at 2,500 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 liters (4.9 US.qts, 4.0 Imp. qts)
Fuel consumption180 g/HPh
PTO shaft rotationCounterclockwise (from PTO shaft side)

Dimensions and Weight

Length, mm (in)420 (16.5)445 (17.5)460 (18.1)465 (18.3)
Width, mm (in)405 (15.9)
Height, mm (in)470 (18.5)
Dry weight, kg (lb)48.0 (105.8)
weight, kg (lb)
53.0 (116.9)

Cylinder Block and Head

Cylinder block
Compression ratio:19.0:1
Bore x Stroke76.0 mm X 70.0 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 liters (1.2 US.qts, 1.0 Imp. qts)
Oil pressure3.9-5.2 kg/cm2 (55.5-74.0 psi) at 3,600 rpm
Resistance2.0 ±0.5 Ω
Starter motor
Brush length10.0 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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We try to use verified sources and official documentation, however, differences between sources or errors in entering information may occur. We do not provide advice on technical issues related to the engines operation or repair. We do not recommend using provided information for engines repairing engines or spare parts ordering, use only official service manuals and spare-parts catalogs.


  1. Bonjour,

    Nous sommes MECANHYDRO, une entreprise de mécanique hydraulique basé en Savoie.

    Je suis à la recherche d’un joint spi qui se monte sur un moteur Honda GD320, je vous transmets les dimensions du joint.
    – 37 intérieure x 64 extérieur 10 épaisseur


  2. I have a gd 410 9 HP to belt drive pressure washer at 3500 psi, can you please tell me how much pressure the Hp the gd320 would put out please. Thank you. Kenny. Fife pressure cleaning services.

  3. There is a Honda GD-320 diesel generator for sale on Facebook for 2190.00. Precious little info is available. I noticed it runs at 3600 rpm. As most diesels run at 1800 rpm I question its reliability. Also I understand that this would be an older unit and parts could be an issue Your opinion would be appreciated

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