Honda GD1250

Honda GD1250 diesel engineThe Honda GD1250 is a 1.25 l (1,235 cc, 75.6 cu-in) three-cylinder water-cooled 4-stroke diesel engine, manufactured by Honda Motor Company for general-purpose applications.

An 82 mm (3.23 in) cylinder bore and 78 mm (3.07 in) piston stroke give the engine a total of 1,235 cc (75.6 cu-in) of displacement. Compression ratio rating is 18:1.

It produced up to 24 HP (16.4 kW) of maximum output (modification SH3). The maximum torque is 55.9 N·m (5.7 kg·m, 41.22 ft·lb) at 2,200 rpm.

General information

Engine Specifications
Model GD1250
Type 4-stroke, OHV, three cylinder
Displacement 1,235 cm 3 (75.6 cu-in)
Max. horsepower SH1: 20 HP (14.9 kW) at 2,600 rpm
SH2: 22 HP (16.4 kW) at 3,000 rpm
SH3: 24 HP (17.9 kW) at 3,600 rpm
Max. torque (crank PTO) SH1: 64.7 N·m (6.6 kg·m, 47.73 ft·lb) at 2,600 rpm
SH2: 61.8 N·m (6.3 kg·m, 45.56 ft·lb) at 2,000 rpm
SH3: 55.9 N·m (5.7 kg·m, 41.22 ft·lb) at 2,200 rpm
Firing order 1-3-2 (1-2-3 from timing belt side)
Injection timing SH1, SH2: B.T.D.C 15°
SH3: B.T.D.C 18°
Cooling system Liquid-cooling
Lubricating system Forced oil by trochoid pump
Starting system Starter motor
Fuel used Diesel fuel
Fuel tank capacity 20.0 l (5.28 US. Gal, 4.40 Imp. Gal.)
Fuel consumption SH1: 180 g/psh (18 HP/2,600 prm)
SH2: 194 g/psh (20 HP/3,000 prm)
SH3: 214 g/psh (22 HP/3,600 prm)
PTO shaft rotation Counterclockwise (from PTO shaft side)

Dimensions and Weight

SH1 SH2 SH3
Length, mm (in) 520 (20.5)
Width, mm (in) 415 (16.3)
Height, mm (in) 540 (21.3) 555 (21.9)
Dry weight, kg (lb) 100.0 (220.5)

Cylinder Block and Head

Cylinder block
Compression ratio: 18:1
Bore x Stroke 82 mm X 78 mm (2.99 x 3.07 in)
Sleeve internal diameter 82.000-82.017 mm (3.2283-3.2290 in)
Piston skirt outer diameter 81.930-81.950 mm (3.225-3.226 in)
Number of piston rings (compression / oil): 2 / 1
Ring side clearance Top 0.085-0.115 mm (0.0033-0.0045 in)
Second 0.055-0.085 mm (0.0022-0.0022 in)
Oil 0.020-0.055 mm (0.0008-0.0022 in)
Ring end gap Top 0.20-0.40 mm (0.008-0.016 in)
Second 0.20-0.40 mm (0.008-0.016 in)
Oil 0.20-0.40 mm (0.008-0.016 in)
Piston pin outer diameter 22.994-23.000 mm (0.9053-0.9055 in)
Connecting rod small end ID 23.010-23.028 mm (0.9060-0.9066 in)
Cylinder Head
Distortion of cylinder head 0.05 mm (0.002 in)
Valve Arrangement: OHV
Valves: 2
Stem outer diameter (standard): INTAKE 6.575-6.590 mm (0.2589-0.2594 in)
EXHAUST 6.545-6.560 mm (0.2577-0.2583 in)
Guide internal diameter INTAKE / EXHAUST 6.600-6.615 mm (0.2598-0.2604 in)
Spring free length 38.1 mm (1.33 in)
Cam lobe height INTAKE / EXHAUST 39.538-39.938 mm (1.5566-1.5724 in)
Valve rocker arm internal diameter 16.012-16.030 mm (0.6304-0.6311 in)
Rocker arm shaft outer diameter 15.976-16.994 mm (0.6290-0.6691 in)

Tightening torque specs

Tightening torque specs
Camshaft holder bolts 22 Nm; 2.2 kg·m; 16 ft·lb
Head cover nuts 10 Nm; 1.0 kg·m; 7 ft·lb
Cylinder head bolts (M12) Step 1: 45 Nm; 4.5 kg·m; 32 ft·lb
Step 2: Turn all bolts 90°
Step 3: Turn all bolts 90° once more
Cylinder head bolts (M8) 30 Nm; 3.0 kg·m; 22 ft·lb
Timing belt driven pulley bolt 38 Nm; 3.8 kg·m; 27 ft·lb
Timing belt adjuster bolt 43 Nm; 4.3 kg·m; 31 ft·lb
Crankshaft bearing cap bolts 68 Nm; 6.8 kg·m; 49 ft·lb
Connecting rod cap nuts 32 Nm; 3.2 kg·m; 23 ft·lb
Rear end plate bolts 55 Nm; 5.5 kg·m; 40 ft·lb
Flywheel bolts 115 Nm; 11.5 kg·m; 83 ft·lb
Flywheel housing 55 Nm; 5.5 kg·m; 40 ft·lb
Oil filter holder 55 Nm; 5.5 kg·m; 40 ft·lb
Oil filter cartridge 22 Nm; 2.2 kg·m; 16 ft·lb
Fuel pipe nuts 22.5 Nm; 2.25 kg·m; 16.3 ft·lb
Fuel joint bolts 22.5 Nm; 2.25 kg·m; 16.3 ft·lb
Injection nozzle nuts Step 1: 5 Nm; 0.5 kg·m; 3.6 ft·lb
Step 2:10 Nm; 1.0 kg·m; 7 ft·lb
Governor shaft 43 Nm; 4.3 kg·m; 31 ft·lb
Glow plugs 17.5 Nm; 1.75 kg·m; 12.7 ft·lb
Glow plug nuts 1.25 Nm; 0.125 kg·m; 0.9 ft·lb
Injection pump nut and bolts 22 Nm; 2.2 kg·m; 16 ft·lb
Oil pressure switch 20 Nm; 2.0 kg·m; 14 ft·lb
Drain plug bolt 45 Nm; 4.5 kg·m; 32 ft·lb
Thermostat switch 22.5 Nm; 2.25 kg·m; 16.3 ft·lb
Crankshaft pulley 115 Nm; 11.5 kg·m; 83 ft·lb

Service Information

Engine
Maximum speed SH1: 2,750 rpm
SH2: 3,120 rpm
SH3: 3,740 rpm
Idle speed 800 rpm
Cylinder compression 27.0 kg/cm2 (384 psi) at 200 rpm
Valve clearance
Intake valve 0.20 ± 0.02 (0.006 ± 0.00078)
Exhaust valve 0.20 ± 0.02 (0.006 ± 0.00078)
Oil system
Oil type Diesel oil (API Service Classification CC or CD)
Recommended oil SAE 10W-30
Oil capacity SH1: 2.9 l (3.07 US. qt, 2.55 Imp. qt.)
SH2, SH3: 4.8 l (5.07 US. qt, 4.22 Imp. qt.)
Oil pressure 4.0 kg/cm2 (57 psi) at 800 rpm
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3 Comments

  1. Is it possible to buy a good-condition used, new, or rebuilt GD1250 Diesel engine? Where and How much?

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