1987 Yamaha YZ490
Specifications and workshop reference information for the 1987 Yamaha YZ490, 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 | Air-cooled 2-stroke single-cylinder |
| Displacement | 487 cc |
| Bore × Stroke | 87.0 mm × 82.0 mm |
| Compression Ratio | 6.8:1 |
| Maximum Power | Approx. 55 hp |
| Maximum Torque | Approx. 58 Nm |
| Carburetor | Mikuni VM38SS |
| Lubrication | Premix |
| Fuel Mix Ratio | 32:1 |
| Ignition | CDI (Capacitor Discharge Ignition) |
| 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 | 2.952 |
| Final Reduction | 3.538 |
| Overall Reduction | — |
Dimensions
| Overall Length | 2200 mm |
| Overall Width | 820 mm |
| Overall Height | 1270 mm |
| Wheelbase | 1490 mm |
| Ground Clearance | 335 mm |
| Fuel Tank Capacity | 9.0 L |
Chassis
| Frame Type | Steel single cradle |
| Caster Angle | 27.5° |
| Trail | 118 mm |
| Front Suspension | Telescopic forks (conventional) |
| Rear Suspension | Monocross swingarm |
| Front Suspension Travel | 300 mm |
| Rear Suspension Travel | 300 mm |
Brakes & Wheels
| Front Tire | 3.00-21 |
| Rear Tire | 5.10-18 |
| Front Brake | Single disc |
| Rear Brake | Drum |
490cc Other Specs
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