The 1988 Yamaha YZ250 is a legendary motocross bike featuring a 249cc liquid-cooled two-stroke engine, 43mm conventional forks, Monoshock rear suspension, and distinctive yellow and black racing livery. This manual covers maintenance, specifications, operation procedures, and troubleshooting for this classic competition motorcycle.
Complete technical specifications for the 1988 Yamaha YZ250 motocross bike.
| Component | Specification |
|---|---|
| Engine Type | 249cc liquid-cooled 2-stroke single |
| Bore x Stroke | 68.0mm x 68.6mm |
| Compression Ratio | 8.6:1 |
| Carburetor | Mikuni VM38SS |
| Ignition | CDI |
| Transmission | 5-speed constant mesh |
| Final Drive | 520 chain |
| Front Suspension | 43mm conventional forks, 11.8" travel |
| Rear Suspension | Monoshock, 12.6" travel |
| Front Brake | Single disc 240mm |
| Rear Brake | Single drum 130mm |
| Dry Weight | 220 lbs (99.8 kg) |
| Fuel Capacity | 2.4 gallons (9.1 liters) |
Proper maintenance procedures for the 249cc two-stroke engine.
WARNING! Always allow engine to cool before performing maintenance. Use proper safety equipment.
Frame geometry and suspension setup for optimal handling.
Front Forks: Oil capacity 435cc per leg, 10wt fork oil
Rear Shock: Nitrogen pressure 142-213 psi, spring preload adjustable
CDI ignition and lighting system specifications.
| Component | Specification |
|---|---|
| Ignition Timing | 1.8mm BTDC at 5000 RPM |
| Spark Advance | 25° at 8000 RPM |
| Stator Output | 60W at 5000 RPM |
| Battery | Not applicable (magneto only) |
| Headlight | 35W/35W halogen |
| Tail Light | 5W/21W |
Mikuni VM38SS carburetor settings and maintenance.
Tip: Adjust jetting for altitude and temperature conditions.
5-speed gearbox specifications and maintenance.
Front disc and rear drum brake maintenance.
CAUTION! Always test brakes after maintenance before riding.
Scheduled maintenance intervals for competition use.
| Service | Interval |
|---|---|
| Air Filter Cleaning | Every race or 8 hours |
| Transmission Oil | Every 10 race hours |
| Spark Plug | Every 20 hours |
| Piston Replacement | Every 40 race hours |
| Fork Oil | Every 30 hours |
| Wheel Bearing Check | Every 25 hours |
| Swingarm Bearing | Every 50 hours |
Common issues and solutions for the YZ250.
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| Hard starting | Fouled plug, stale fuel | Replace spark plug, drain old fuel |
| Poor performance | Clogged air filter, incorrect jetting | Clean filter, adjust carburetor |
| Transmission noise | Low oil level, worn gears | Check oil, inspect transmission |
| Overheating | Low coolant, lean jetting | Check coolant level, richen mixture |
| Poor suspension | Worn bushings, incorrect oil level | Replace bushings, service forks/shock |
Genuine Yamaha parts and recommended accessories.
Important safety precautions for operation and maintenance.
WARNING! This is a competition vehicle not intended for street use. Operate only in designated areas.
Service Support: Contact authorized Yamaha dealer for technical assistance and genuine parts.