The Subaru-Robin EX13D is a 126 cc (7.69 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 EX13D engine has an OHС (overhead camshaft) design; high compression ratio for better fuel efficiency; horizontal draft, float type carburetor; recoil starter and transistorized magneto ignition system.
Cylinder bore is 58.0 mm (2.28 in) and piston stroke is 48.0 mm (1.89 in), compression ratio rating is 8.5:1. The engine produced 2.9 4.4 PS (3.2 kW; 4.3 HP) at 4,000 rpm of maximum horsepower and 2.6 PS (1.9 kW; 2.5 HP) at 3,000 rpm or 3.0 PS (2.2 kW; 3.0 HP) at 3,600 rpm of continuous output power. Maximum torque is 8.1 N·m (0.8 kg·m, 6 ft·lb) at 2,500 rpm.
General information
| Engine Specifications | |
| Model | EX13D |
| Type | 4-stroke, OHC, single cylinder |
| Displacement | 126 cm 3 (7.7 cu-in) |
| Max. horsepower | 4.4 PS (3.2 kW; 4.3 HP) at 4,000 rpm |
| Max. torque (crank PTO) | 8.1 N·m (0.8 kg·m, 6 ft·lb) at 2,500 rpm |
| Carburetor | Horizontal draft, float type carburetor |
| Cooling system | Forced-air |
| Ignition system | Transistorized magneto ignition |
| Lubricating system | Splash |
| Starting system | Recoil starter |
| Stoping system | Ignition primary circuit ground |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Fuel tank capacity | 2.7 L (0.71 US. gal. 0.59 Imp. gal.) |
| Fuel consumption | 367 g/kWH |
| PTO shaft rotation | Counterclockwise (from PTO shaft side) |
Cylinder Block and Head
The EX13D has cast iron cylinder sleeve, ball bearing supported forged steel crankshaft, improved piston design. The piston has two compression rings and one oil ring.
| Cylinder block | ||
| Compression ratio: | 8.5:1 | |
| Bore x Stroke | 58.0 X 48.0 mm (2.28 x 1.89 in) | |
| Sleeve internal diameter | 58.000-58.020 mm (2.2835-2.2842 in) | |
| Piston skirt outer diameter | 57.980-58.000 mm (2.2827-2.2835 in) | |
| Number of piston rings (compression / oil): | 2 / 1 | |
| Ring side clearance | Top | 0.035-0.080 mm (0.0014-0.0031 in)) |
| Second | 0.035-0.080 mm (0.0014-0.0031 in) | |
| Oil | 0.020-0.075 mm (0.0008-0.003 in) | |
| Ring end gap | Top/Second | 0.15-0.35 mm (0.0059-0.0138 in) |
| Oil | 0.20-0.40 mm (0.0079-0.0157 in) | |
| Connecting rod small end ID | 13.010-13.020 mm (0.5122-0.5126 in) | |
| Connecting rod big end ID | 30.000-30.016 mm (1.1811-1.1817 in) | |
| Piston pin outer diameter | 12.991-13.009 mm (0.5115-0.5122 in) | |
| Crankshaft crankpin outer diameter | 29.967-29.980 mm (1.1798-1.1803 in) | |
| Crankshaft main journal diameter | №1 | 27.988-24.997 mm (1.1019-0.9841 in) |
| №2 | 24.988-24.997 mm (0.9838-0.9841 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 | 29.028-29.128 mm (1.1428-1.1468 in) |
| EXHAUST | 29.028-29.128 mm (1.1428-1.1468 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 | 13-15 Nm; 1.3-1.5 kg·m; 9.4-10.8 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
| Engine | |
| Cylinder compression | 3.5 kg/cm2 |
| 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 | |
| Oil type | 4-stroke or an equivalent (SE or SF) |
| Recommended oil | SAE 10W-30 |
| Oil capacity | 0.6 L (0.63 US. qt, 0.53 Imp. qt.) |
| Ignition system | |
| Spark plug | NGK: BR-6HS; CHAMPION: RL86C |
| Spark plug gap | 0.6-0.7 mm (0.0236-0.0276 in) |
Author:
I’m looking for guidance as to number and shape of the carburettor gaskets for the robin EX13 especially the complicated one 2nd from the engine block, thanks for helping me so far
Also looking for the same thing no luck yet