Subaru-Robin EX30D

Subaru-Robin EX30DThe Subaru-Robin EX30D is a 287 cc (17.51 cu·in) single-cylinder air-cooled 4-stroke internal combustion small gasoline engine manufactured by Industrial Products division of Subaru Corporation for general-purpose applications.

The Subaru-Robin EX30D engine has an OHС (overhead camshaft) design; high compression ratio for better fuel efficiency; horizontal draft, float type carburetor; recoil starter or electric starter as option and transistorized magneto ignition system.

A 75.0 mm (2.95 in) cylinder bore and 65.0 mm (2.56 in) piston stroke give the motor a total 265 cc (16.17 cu-in) of displacement. The engine produced 9.0 PS (6.6 kW; 8.9 HP) at 4,000 rpm of maximum horsepower.

General information

Engine Specifications
Model EX30D
Type 4-stroke, OHC, single cylinder
Displacement 287 cm 3 (17.51 cu-in)
Max. horsepower 9.0 PS (6.6 kW; 8.9 HP) at 4,000 rpm
Max. torque (crank PTO)
Carburetor Horizontal draft, float type carburetor
Cooling system Forced-air
Ignition system Transistorized magneto ignition
Lubricating system Splash
Starting system Recoil or electric starter
Stoping system Ignition primary circuit ground
Fuel used Unleaded gasoline (octane number 86 or higher)
PTO shaft rotation Counterclockwise (from PTO shaft side)

Cylinder Block and Head

The EX30D has cast iron cylinder sleeve, ball bearing supported forged steel crankshaft, improved piston design. The piston has single compression rings and a single oil ring.

Cylinder block
Bore x Stroke 75.0 x 65.0 mm (2.95 x 2.56 in)
Sleeve internal diameter 75.000-75.019 mm (2.9528-2.9535 in)
Piston skirt outer diameter 74.980-75.000 mm (2.952-2.9528 in)
Number of piston rings (compression / oil): 1 / 1
Ring side clearance Top 0.035-0.080 mm (0.0014-0.0031 in))
Oil 0.0100-0.205 mm (0.0004-0.0081 in)
Ring end gap Top 0.10-0.30 mm (0.0039-0.0118 in)
Oil 0.20-0.70 mm (0.0079-0.0276 in)
Connecting rod small end ID 18.010-18.020 mm (0.7091-0.7094 in)
Connecting rod big end ID 34.500-34.516 mm (1.3583-1.3589 in)
Piston pin outer diameter 17.992-18.000 mm (0.7083-0.7087 in)
Crankshaft crankpin outer diameter 34.467-34.480 mm (1.357-1.3575 in)
Crankshaft main journal diameter 29.998-29.997 mm (1.181-1.181 in)
Cylinder Head
Warpage (limit) 0.10 mm (0.004 in)
Valve Arrangement: OHC
Valves: 2
Stem outer diameter (standard): INTAKE 5.440-5.455 mm (0.2142-0.2148 in)
EXHAUST 5.425-5.445 mm (0.2136-0.2144 in)
Valve spring free length: 27.4 mm (1.0787 in)
Camshaft lobe height: INTAKE 29.431-29.531 mm (1.1587-1.1626 in)
EXHAUST 29.431-29.531 mm (1.1587-1.1626 in)

Tightening torque specs

Tightening torque specs
Cylinder head M8 × 68 flange bolt (Re-use) 25-27 Nm; 2.5-2.7 kg·m; 18.1-19.5 ft·lb
Cylinder head M8 × 68 flange bolt (New) 28-30 Nm; 2.8-3.0 kg·m; 20.3-21.7 ft·lb
Cylinder head M8 × 35 flange bolt 17-19 Nm; 1.7-1.9 kg·m; 12.3-13.7 ft·lb
Connecting rod bolt 17-20 Nm; 1.7-2.0 kg·m; 12.3-14.5 ft·lb
Main bearing cover bolts 22-24 Nm; 2.2-2.4 kg·m; 16.2-17.7 ft·lb
Flywheel nut 59-64 Nm; 5.9-6.4 kg·m; 42.7-46.3 ft·lb

Service Information

Cylinder compression 5.0 kg/cm2
Valve clearance
Intake valve clearance 0.11-0.16 mm (0.0043-0.0063 in)
Exhaust valve clearance 0.11-0.16 mm (0.0043-0.0063 in)
Oil system
Oil type 4-stroke or an equivalent (SE or SF)
Recommended oil SAE 10W-30
Oil capacity 1.0 L (1.06 US. qt, 0.88 Imp. qt.)
Fuel system
Type: Horizontal draft, float type carburetor
Main jet: #98
Pilot screw opening: 1-1/2 turns out
Ignition system
Spark plug NGK: BR-6HS;
Spark plug gap 0.6-0.7 mm (0.0236-0.0276 in)
Spark plug torque: 25 N·m (2.5 kg·m, 18.4 ft·lb)
Ignition coil air gap 0.3-0.5 mm (0.0118-0.0118 in)
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