Segment:
High-performance Motocross/Off-Road competition motorcycle.
Competitors:
KTM 250 SX, Honda CR250R (historically), Suzuki RM250 (historically), Kawasaki KX250.
Engine Type:
Liquid-cooled, 2-stroke, reed valve inducted, single-cylinder.
Performance Focus:
Emphasis on peak power delivery, light weight, and agile handling for competitive off-road riding.
Manual Utility:
Indispensable resource for owners seeking to maintain, repair, and optimize their YZ250 for peak performance and longevity.
General Coverage:
Comprehensive service, repair, and maintenance information for the Yamaha YZ250 motorcycle.
Estimated Pages:
Detailed page count not specified in product description; however, workshop manuals are typically extensive, ranging from 300-800+ pages.
Type:
Workshop Service Repair Manual
Language:
English (assumed, typical for this product)
Format:
Digital Download (PDF)
Engine:
Complete engine disassembly, assembly, troubleshooting, tuning, and repair for the 2-stroke engine.
Transmission:
Clutch, gearbox, and shift mechanism maintenance, repair, and adjustment.
Fuel System:
Carburetor (including jetting and adjustment), fuel tank, fuel lines, and fuel pump (if applicable).
Cooling System:
Radiator, hoses, thermostat, and coolant specifications.
Ignition System:
CDI unit, ignition coil, spark plug, timing specifications, and troubleshooting.
Exhaust System:
Exhaust pipe, silencer, and packing maintenance.
Suspension:
Front forks (including damping, seals, and oil levels), rear shock absorber (including spring preload and damping adjustments), linkage maintenance.
Brakes:
Front and rear hydraulic disc brake systems, including caliper, master cylinder, brake lines, pads, fluid specifications, and bleeding procedures.
Wheels And Tires:
Wheel bearing maintenance, spoke tension, tire pressure, and recommended tire sizes.
Electrical System:
Lighting, horn, battery, wiring diagrams, and troubleshooting.
Frame And Bodywork:
Chassis inspection, plastics, seat, handlebars, and footpegs.
Maintenance:
Routine maintenance, including oil changes (premix ratio), air filter cleaning/replacement, spark plug inspection, chain adjustment, and lubrication.
Troubleshooting:
Diagnostic procedures for common starting issues, running problems, and component failures, supported by detailed explanations.
Repair:
Step-by-step instructions for engine rebuilds, suspension overhauls, brake system repairs, and component replacements.
Adjustments:
Detailed procedures for carburetor tuning, clutch adjustment, chain slack, and suspension settings.
Torque Specifications:
Essential torque values for critical fasteners across all systems.
Depth:
Comprehensive, suitable for both home mechanics and professional technicians. Covers everything from basic adjustments to full engine and chassis rebuilds.
Configuration:
Single-cylinder, two-stroke
Displacement:
249cc (specific displacement may vary slightly by model year, but consistently around 249cc)
Bore X Stroke:
Typically 66.4 mm x 72.0 mm (varies slightly by generation)
Cooling System:
Liquid-cooled
Induction:
Reed valve intake
Power Valve System:
Yamaha Power Valve System (YPVS) for optimized power delivery across the RPM range.
Horsepower:
Estimated 45-50+ HP (highly dependent on model year and tuning)
Torque:
Estimated 30-35+ ft-lbs (highly dependent on model year and tuning)
Carburetor Type:
Mikuni VM Series (e.g., VM38) or Keihin PWK (depending on model year).
Fuel Mixture:
Pre-mix (gasoline and 2-stroke oil). Typical ratio 32:1 or 40:1, refer to manual for specific year recommendation.
Oil Change Premix:
Premix is added with fuel; regular checking of the oil reservoir (if equipped with oil injection, though YZ250 is typically pre-mix) and ensuring proper mix ratio is critical.
Air Filter:
Recommended cleaning or replacement after every few rides, or more frequently in dusty conditions. Specific interval in manual.
Spark Plug:
Inspection and cleaning/replacement at regular intervals, typically every 10-20 hours of riding. Manual will specify plug type and gap.
Chain Adjustment:
Check and adjust slack before each ride or every few rides, depending on riding conditions. Lubrication recommended regularly.
Fork Oil:
Recommended fork oil change and seal inspection periodically (e.g., every 20-30 hours or annually). Manual details type and volume.
2-Stroke Oil:
High-quality synthetic 2-stroke racing oil recommended. Examples: Yamalube 2R, Motul 800, Bel-Ray H1-R. Manual specifies approved types.
Gearbox Oil:
Yamaha recommends Yamalube Gear Oil. Manual specifies viscosity (e.g., 10W-30) and capacity.
Coolant:
Permanent type antifreeze (ethylene glycol-based) mixed with distilled water, typically 50/50 ratio. Manual specifies type and capacity.
Brake Fluid:
DOT 4 hydraulic brake fluid recommended. Manual specifies type and change interval.
Common Wear Items:
Piston rings, clutch plates, brake pads, wheel bearings, swingarm/pivot bearings, fork seals, exhaust packing.
Carburetor Tuning:
Carburetor jetting can be sensitive to altitude, temperature, and modifications. Manual provides baseline settings and troubleshooting.
Power Valve Maintenance:
The YPVS mechanism requires periodic cleaning to prevent carbon buildup and ensure smooth operation.
