1984 Yamaha YZ250
Specifications and workshop reference information for the 1984 Yamaha YZ250, including engine, chassis, service data and setup details.
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-cylinder, reed valve |
| Displacement | 249 cc |
| Bore × Stroke | 70.0 × 64.0 mm |
| Compression Ratio | Approx. 7.8:1 |
| Maximum Power | Approx. 42 hp @ 8500 rpm |
| Maximum Torque | Approx. 35 Nm @ 7500 rpm |
| Carburetor | Mikuni VM38SS |
| Lubrication | Premix |
| Fuel Mix Ratio | 20:1 – 32:1 |
| Ignition | CDI |
| Spark Plug | NGK BR8ES |
| Spark Plug Gap | 0.6 – 0.7 mm |
Transmission
| Transmission Type | 5-speed manual |
| Clutch | Wet multi-plate |
| Primary Reduction | Approx. 2.952 |
| Final Reduction | Approx. 3.538 |
| Overall Reduction | Varies by gear |
Dimensions
| Overall Length | Approx. 2160 mm |
| Overall Width | Approx. 825 mm |
| Overall Height | Approx. 1220 mm |
| Wheelbase | Approx. 1465 mm |
| Ground Clearance | Approx. 340 mm |
| Fuel Tank Capacity | Approx. 9.0 L |
Chassis
| Frame Type | Steel tubular, single backbone |
| Caster Angle | Approx. 27° |
| Trail | Approx. 115 mm |
| Front Suspension | Telescopic fork (Kayaba) |
| Rear Suspension | Monocross single shock |
| Front Suspension Travel | Approx. 300 mm |
| Rear Suspension Travel | Approx. 300 mm |
Brakes & Wheels
| Front Tire | 80/100-21 |
| Rear Tire | 110/90-19 |
| Front Brake | Hydraulic disc |
| Rear Brake | Drum |
250cc Other Specs
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