Subaru-Robin EX27D

Subaru-Robin EX27D engineThe Robin-Subaru EX27D is a 265 cc, (16.2 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 EX27D 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. This engine used a horizontal draft, float type carburetor, transistorized magneto ignition system, splash type lubricating system, and forced-air cooling system. The EX27D is equipped with a 6.1 L (1.61 US. gal. 1.34 Imp. gal.) fuel tank.

This engine produced 9.0 PS (6.6 kW; 8.9 HP) at 4,000 rpm of horsepower and 18.6 N·m (1.9 kg·m, 13.7 ft·lb) at 2,500 rpm of torque.

General information

Engine Specifications
Engine model Robin-Subaru EX27D
Engine type 4-stroke, OHC, single-cylinder
Displacement 265 cm3, (16.17 cu·in)
Max. horsepower 9.0 PS (6.6 kW; 8.9 HP) at 4,000 rpm
Max. torque 18.6 N·m (1.9 kg·m, 13.7 ft·lb) at 2,500 rpm
Cooling system Forced air
Lubricating system Splash type
Ignition system Transistorized magneto ignition
Fuel system Horizontal draft, float type carburetor
Fuel tank capacity 6.1 L (1.61 US. gal. 1.34 Imp. gal.)
Fuel used Unleaded gasoline (octane number 86 or higher)
Starting system Recoil or electric starter (option)
Stoping system Ignition primary circuit ground
Governor Centrifugal govervor
Charging capacity 12-1A, 3A, 16.7A (option)
PTO shaft rotation Counterclockwise (from PTO shaft side)
Dimensions (L x W X H) 351 x 420 x 410 mm (13.8 x 16.5 x 16.1 in)
Dry weight 21.0 kg (46.3 lbs)

Cylinder Block and Head

A 75.0 mm (2.95 in) cylinder bore and 60.0 mm (2.36 in) piston stroke give the EX27D engine a total of 265 cc of displacement. Compression ratio rating is 8.3:1. 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 two compression rings.

Cylinder block
Compression ratio: 8.3:1
Cylinder bore: 75.0 mm (2.95 in)
Piston stroke: 60.0 mm (2.36 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): 2/1
Connecting rod big end diameter (standard): 34.500-34.516 mm (1.3583-1.3589 in)
Connecting rod small end diameter (standard): 18.010-18.020 mm (0.7091-0.7094 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 (Second): 0.035-0.080 mm (0.0014-0.0031 in)
Side clearance (Oil): 0.010-0.065 mm (0.0004-0.0026 in)
Ring end gap (Top): 0.10-0.30 mm (0.0039-0.0118 in)
Ring end gap (Second): 0.20-0.40 mm (0.0079-0.0157 in)
Ring end gap (Oil): 0.10-0.30 mm (0.0039-0.0118 in)
Crankshaft main journal diameter: 29.998-29.997 mm (1.181-1.181 in)
Crankpin journal diameter: 34.467-34.480 mm (1.357-1.3575 in)
Crankshaft center distance: 30 mm (1.18 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): 29.028-29.128 mm (1.1428-1.1468 in)
Camshaft lobe height (EXHAUST): 29.028-29.128 mm (1.1428-1.1468 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 or 10W-40 is recommended for the EX27D, refilling oil capacity is 1.0 L (1.06 US. qt, 0.88 Imp. qt.). Recommended spark plug are NGK: BR-6HS or CHAMPION RL86C with 0.6-0.7 mm (0.0236-0.0276 in) spark plug gap.

The valve clearance is 0.12-0.15 mm (0.0047-0.0059 in) for intake and exhaust valves. Standard cylinder compression is 3.5 kg/cm2 at 500 rpm.

Cylinder compression: 3.5 kg/cm2 at 500 rpm
Valve clearance
Intake valve clearance: 0.12-0.15 mm (0.0047-0.0059 in)
Exhaust valve clearance: 0.12-0.15 mm (0.0047-0.0059 in)
Oil system
Lubrication system: Splash type
Oil consupumtion: 5-10 ml/h
Oil type: 4-stroke engine oil, API service classification SE
Recommended oil: SAE 10W-30 or 10W-40
Oil capacity: 1.0 L (1.06 US. qt, 0.88 Imp. qt.)
Fuel system
Type: Horizontal draft, float type carburetor
Ignition system
Type: Transistorized magneto ignition
Spark plug: NGK: BR-6HS;
CHAMPION: RL86C
Spark plug gap: 0.6-0.7 mm (0.0236-0.0276 in)

1 Comment

  1. I would like to buy to of your engines that at least have 20 foot pounds of torque or your best deal for a 320cc at least to be great to get like something in ball park of 420cc

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