Subaru-Robin EX30D

Subaru-Robin EX30D engineThe Robin-Subaru EX30D is a 287 cc, (17.5 cu·in) natural aspirated single-cylinder four-stroke air-cooled internal combustion small gasoline engine with a horizontal shaft, manufactured by the Industrial Products division of Subaru Corporation for general-purpose applications.

The Subaru EX21D engine has a single-cylinder, heavy-duty chain-driven overhead camshaft (OHC) system, a sophisticated mechanical compression release system, and a heavy-duty recoil starter or electric starter. This engine used a horizontal draft, float type carburetor, transistorized magneto ignition system, splash type lubricating system, and forced-air cooling system. The EX30D is not equipped with a fuel tank. The EX30D engine produced 9.0 PS (6.6 kW; 8.9 HP) at 4,000 rpm of maximum horsepower.

General information

Engine Specifications
Engine model Robin-Subaru EX30D
Engine type 4-stroke, OHC, single-cylinder
Displacement 287 cm3, (17.51 cu·in)
Max. horsepower 9 PS (6.6 kW; 8.9 HP) at 4,000 rpm
Cooling system Forced air
Lubricating system Splash type
Ignition system Transistorized magneto ignition
Fuel system Horizontal draft, float type carburetor
Fuel used Unleaded gasoline (octane number 86 or higher)
Starting system Recoil or electric starter
Stoping system Ignition primary circuit ground
Governor Centrifugal govervor
PTO shaft rotation Counterclockwise (from PTO shaft side)
Dimensions (L x W X H) 415 x 424 x 319 mm (16.3 x 16.7 x 12.6 in)
Dry weight 21.0 kg (46.3 lbs)

Cylinder Block and Head

Cylinder bore and piston stroke are 75.0 mm (2.95 in) and 65.0 mm (2.56 in), respectively. The engine uses cast iron cylinder liner and large ball bearings on both ends of crankshaft for maximum stability under demanding loads. The piston is equipped with single oil and single compression rings.

Cylinder block
Cylinder bore: 75.0 mm (2.95 in)
Piston stroke: 65.0 mm (2.56 in)
Cylinder internal diameter (standard): 75.000-75.019 mm (2.9528-2.9535 in)
Piston skirt outer diameter (standard): 74.980-75.000 mm (2.952-2.9528 in)
Number of piston rings (compression / oil): 1/1
Connecting rod big end diameter (standard): 34.500-34.516 mm (1.3583-1.3589 in)
Connecting rod small end diameter (standard): 18.010-18.021 mm (0.7091-0.7095 in)
Piston pin diameter: 17.992-18.000 mm (0.7083-0.7087 in)
Side clearance (Top): 0.035-0.080 mm (0.0014-0.0031 in)
Side clearance (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)
Ring end gap (Oil): 0.20-0.70 mm (0.0079-0.0276 in)
Crankshaft main journal diameter: 29.991-30.000 mm (1.1807-1.1811 in)
Crankpin journal diameter: 34.467-34.480 mm (1.357-1.3575 in)
Crankshaft center distance: 32.5 mm (1.28 in)
Cylinder head
Valve arrangement: OHC, chain driven
Valves: 2
Valve steam diameter (INTAKE): 5.440-5.455 mm (0.2142-0.2148 in)
Valve steam diameter (EXHAUST): 5.425-5.445 mm (0.2136-0.2144 in)
Valve spring free length (INTAKE): 27.4 mm (1.0787 in)
Valve spring free length (EXHAUST): 27.4 mm (1.0787 in)
Camshaft lobe height (INTAKE): 29.431-29.531 mm (1.1587-1.1626 in)
Camshaft lobe height (EXHAUST): 29.431-29.531 mm (1.1587-1.1626 in)

Tightening torque

Tightening torque settings
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 Data

The 4-stroke engine oil, API service classification SE oil with a viscosity of SAE 10W-30 is recommended for the EX30D, refilling oil capacity is 1.0 L (1.06 US. qt, 0.88 Imp. qt.). Recommended spark plug is NGK BR-6HS with 0.6-0.7 mm (0.0236-0.0276 in) spark plug gap.

The valve clearance is 0.11-0.16 mm (0.0043-0.0063 in) for intake and exhaust valves. Standard cylinder compression is 5.0 kg/cm2 at 500 rpm.

Cylinder compression
Cylinder compression: 5.0 kg/cm2 at 500 rpm
Valve clearance
Intake valve clearance (COLD): 0.11-0.16 mm (0.0043-0.0063 in)
Exhaust valve clearance (COLD): 0.11-0.16 mm (0.0043-0.0063 in)
Oil system
Lubrication system: Splash type
Oil consupumtion: 8-13 ml/h
Oil type: 4-stroke engine oil, API service classification SE
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
Type: Transistorized magneto ignition
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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