Segment:
Motocross Competition Motorcycle
Rivals 1988:
Honda CR250R, Suzuki RM250, Kawasaki KX250
Yz250 1988 Features:
Powerful two-stroke engine, aggressive styling, competitive suspension, focused on performance
Intended User:
Motocross racers, off-road enthusiasts, mechanics
Engine:
Complete overhaul, tuning, carburetor, cooling system, lubrication, ignition system
Transmission:
Clutch, gearbox internals, shift mechanism, maintenance
Chassis:
Frame, suspension (front forks, rear shock), steering, wheels, tires
Brakes:
Front and rear brake systems, hydraulic components, adjustments
Electrical:
Wiring diagrams, lighting system, ignition, charging system (if applicable)
Bodywork:
Plastic panels, seat, handlebars, footpegs, removal and installation
Maintenance:
Scheduled maintenance, lubrication points, filter replacement, spark plug checks
Troubleshooting:
Diagnostic charts for common problems, symptom-based solutions
Repair:
Detailed step-by-step repair procedures for all major components
Disassembly Assembly:
Complete instructions for engine, transmission, and chassis component removal and reinstallation
Adjustments:
Carburetor tuning, clutch adjustment, brake adjustments, suspension settings
Depth:
Comprehensive: Covers routine maintenance, detailed repairs, and engine rebuilds. Includes specifications and torque values.
Engine Type:
2-Stroke, Liquid-Cooled, Reed Valve
Displacement:
249 cc (Cubic Centimeters)
Bore X Stroke:
68.0 mm x 68.5 mm
Compression Ratio:
7.6:1 (approximate, can vary slightly)
Horsepower Estimated:
Approx. 40-45 HP (at Crankshaft)
Torque Estimated:
Approx. 25-28 lb-ft (at Crankshaft)
Carburetor Type:
Mikuni VM34SS (likely)
Fuel Type:
Unleaded Gasoline (with appropriate Octane rating, typically 91 or higher)
Fuel Mixture:
2-stroke oil premix (refer to manual for exact ratio, typically 32:1 or 40:1)
Ignition System:
CDI (Capacitor Discharge Ignition)
Cooling Method:
Liquid Cooling
Coolant Type:
Ethylene Glycol based antifreeze (refer to manual for specific mix ratio)
Overall Length:
Refer to specific Yamaha specifications for 1988 YZ250
Overall Width:
Refer to specific Yamaha specifications for 1988 YZ250
Overall Height:
Refer to specific Yamaha specifications for 1988 YZ250
Dry Weight:
Approx. 220 lbs (100 kg)
Wet Weight:
Refer to specific Yamaha specifications for 1988 YZ250 (with fluids)
Front Tire Size:
80/100-21 (typical)
Rear Tire Size:
100/90-18 (typical)
Wheel Base:
Refer to specific Yamaha specifications for 1988 YZ250
Oil Change Frequency:
Refer to manual; typically after specific riding hours or events
Air Filter Cleaning:
Regularly, depending on riding conditions (refer to manual)
Spark Plug Replacement:
Refer to manual; typically based on hours or performance degradation
Top End Rebuild:
Recommended based on riding hours and engine condition (refer to manual for guidelines)
Coolant Spec:
Ethylene Glycol based antifreeze, 50/50 mix with distilled water recommended
Brake Fluid Type:
DOT 3 or DOT 4 Hydraulic Brake Fluid (refer to manual)
Common Wear Items:
Clutch plates, piston rings, air filter, spark plug, chain and sprockets, suspension seals
Carburetor Tuning Challenges:
Can be sensitive to altitude and temperature changes; requires precise jetting.
Engine Bolt Torques:
Detailed torque values for critical engine fasteners provided in the manual.
Suspension Bolt Torques:
Specific torque values for suspension components included.
Yamaha Offroad Legacy:
Yamaha has a long and successful history in motocross and off-road racing, with the YZ line being a cornerstone of their performance offerings.
Yz250 Generations:
The YZ250 has undergone continuous development since its inception, with significant updates in engine technology, suspension, and chassis design throughout the 1980s and beyond.
Manufacturing Location:
Japan
Production Years Relevant
Other Years Covered:
Manual is specific to 1988, but the provided links indicate availability for 1982 and 1985 models.
Motocross Competitiveness:
The YZ250 platform consistently achieved podium finishes and championships throughout its production run, indicating strong design and performance.
Performance Reviews:
Contemporary reviews praised its powerful engine and capable suspension for its time.
Emissions Certification:
N/A (Off-road competition vehicle)
