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1981 Yamaha YZ250
Specifications and workshop reference information for the 1981 Yamaha YZ250.
Note: Specs are compiled from factory data, manuals and owner feedback. Bikes vary — if yours is different, jump into the forum and share it.
General Specifications
| Engine Type | Liquid-cooled 2-stroke single |
| Displacement | 246 cc |
| Bore × Stroke | 70 mm × 64 mm |
| Carburetor | Mikuni VM38 |
| Transmission | 5-speed |
| Final Drive | Chain |
Service Specifications
| Transmission Oil Capacity | 750 cc |
| Spark Plug | NGK B8ES |
| Spark Plug Gap | 0.6 – 0.7 mm |
| Fuel Mix Ratio | 32:1 |
| Idle Speed | Approx 1500 rpm |
Carburetor (Baseline)
| Main Jet | #400 |
| Pilot Jet | #50 |
| Needle | 6FJ6 |
| Float Height | 22 mm |
| Air Screw | 1-1/8 turns out |
Torque Settings
| Spark Plug | 18 N·m |
| Front Axle | 65 N·m |
| Rear Axle | 90 N·m |
Drive
| Chain Size | 520 |
| Standard Sprockets | 13T / 49T |
250cc Other Specs
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