1981 Yamaha YZ250 Specifications and Specs
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 | Single-cylinder, two-stroke, liquid-cooled |
| Displacement | 246 cc |
| Bore × Stroke | 70.0 × 64.0 mm |
| Compression Ratio | Not Published |
| Maximum Power | Not Published |
| Maximum Torque | Not Published |
| Carburetor | Mikuni VM38 | Replacement Options |
| Lubrication | Premix |
| Fuel Mix Ratio | 32:1 | Premix Calculator |
| Ignition | CDI |
| Spark Plug | NGK B8ES |
| Spark Plug Gap | 0.6 – 0.7 mm |
Transmission
| Transmission Type | 5-speed constant mesh |
| Clutch | Wet multi-plate |
| Primary Reduction | Not Published |
| Final Reduction | 13T / 49T |
| Overall Reduction | Not Published |
Dimensions
| Overall Length | Not Published |
| Overall Width | Not Published |
| Overall Height | Not Published |
| Wheelbase | Not Published |
| Ground Clearance | Not Published |
| Fuel Tank Capacity | Not Published |
| Bearing Sizes |
Bearing Finder |
Chassis
| Frame Type | Steel tubular frame |
| Caster Angle | Not Published |
| Trail | Not Published |
| Front Suspension | Telescopic forks | Fork Oil Levels |
| Rear Suspension | Monocross single shock | Rear Suspension Setup |
| Front Suspension Travel | Not Published |
| Rear Suspension Travel | Not Published |
Brakes & Wheels
Service Data
| Transmission Oil Capacity | 750 cc |
| Spark Plug | NGK B8ES |
| Spark Plug Gap | 0.6 – 0.7 mm |
| Idle Speed | Approx. 1,500 rpm |
| Main Jet | #400 |
| Pilot Jet | #50 |
| Needle | 6FJ6 |
| Float Height | 22 mm |
| Air Screw | 1-1/8 turns out |
| Chain Type | 520 |
| Standard Sprockets | 13T / 49T |
| Spark Plug Torque | 18 N·m |
| Front Axle Torque | 65 N·m |
| Rear Axle Torque | 90 N·m |
250cc Other Specs
Community
VMX Owners Forum
Discuss vintage motocross bikes, restorations, tuning and riding.
