This manual covers general information for the 139QMA engine, including the location of the engine number, basic technical specifications, and a complete list of required universal and special tools. Detailed sections describe disassembly and assembly steps, tightening torque values for critical fasteners, and the engine fuel‑supply system.
Additional chapters provide troubleshooting advice for starting problems, maintenance interval recommendations, and safety precautions during repair work. The document is intended for technicians performing service and repair on the engine.
| Starting mode | Kick starting and electric starting |
|---|---|
| Engine type | Four strokes |
| Number of cylinders | Single |
| Combustion chamber | Hemtsphenc |
| Valve structure | O.H.C. chain transmission |
| Cylinder bore x travel (mm) | 539x414 |
| Total displacement (mL) | 49 |
| Compression ratio | 10.5 |
| Maximum power | 2..9/7500 |
| Maximum torque | 29/7000 |
| Idle speed (r/min) | 1900 |
| Lubrication mode | Both pressure and splash |
| Lubricant volume | 0.9L |
| Cooling mode | Forced air cooling |
| Carburetor type | Diaphragm carburetor |
| Ignition type | CDI magneto ignition |
| Ignition time | 13° (1700 r/min) ~28° (800 r/min) |
| Transmission type | Two‑stage reduction |
| First stage reduction ratio | 3.35 |
| Second stage reduction ratio | 3.4 |
The engine number is located at the lower left front of the left crankcase.
The recommended tightening torque for a 5 mm bolt/nut is 45 ~ 0.6 N·m.