Positioning:
The 1995 Yamaha YZ250 was a highly competitive motocross and off-road racing machine, known for its potent two-stroke powerband and agile handling. This manual serves as the definitive guide for owners and mechanics maintaining and repairing this iconic model.
Competitors:
Competed directly with other 250cc two-stroke motocross bikes from manufacturers like Honda (CR250R), Kawasaki (KX250), and KTM (250 EXC/SX). The YZ250 of this era was lauded for its smooth power delivery and refined chassis.
Features:
Liquid-cooled 249cc 2-stroke engine, YPVS (Yamaha Power Valve System) for broad powerband, advanced suspension components, lightweight chassis.
Systems Covered:
Engine, transmission, chassis, suspension, brakes, electrical system, fuel system, cooling system, exhaust system, bodywork, troubleshooting, maintenance.
Pages:
Extensive (exact count not specified, but described as detailed and illustrated).
Type:
Service Repair Workshop Manual
Format:
PDF (Downloadable)
Engine Internal:
Top-end rebuild (piston, rings, cylinder, cylinder head), bottom-end overhaul (crankshaft, connecting rod, bearings, seals), carburetor overhaul and adjustment, ignition system inspection and testing, cooling system maintenance and repair, lubrication system.
Transmission Drivetrain:
Clutch operation and adjustment, gearbox disassembly and assembly, shift mechanism troubleshooting, final drive (chain and sprockets) inspection and maintenance.
Chassis Suspension:
Front fork service and adjustment (compression, rebound damping), rear shock absorber maintenance and rebuild, linkage system lubrication and inspection, frame inspection, steering head bearing service.
Brakes:
Front and rear brake system inspection, hydraulic fluid replacement, caliper service, brake pad replacement, master cylinder and slave cylinder inspection.
Electrical System:
Wiring diagrams, lighting system, ignition coil testing, stator and rotor inspection, battery maintenance, troubleshooting electrical faults.
Routine Maintenance:
Oil and filter changes (if applicable to 2-stroke oil mixture), air filter cleaning and replacement, spark plug replacement and gap adjustment, chain adjustment and lubrication, pre-ride inspections.
Troubleshooting:
Diagnostic procedures for common starting issues, power loss, unusual noises, and system malfunctions. Includes fault finding charts.
Repair Overhaul:
Step-by-step instructions for complete engine disassembly, rebuilding, and reassembly. Detailed procedures for suspension and brake system overhauls.
Depth:
Comprehensive, covering basic maintenance to complete engine rebuilds and advanced diagnostics. Suitable for home mechanics and professional technicians.
Engine Displacement:
249cc
Engine Type:
Liquid-cooled, 2-stroke, Reed Valve
Bore X Stroke:
68.0 mm x 68.5 mm
Compression Ratio:
8.8:1 (approx.)
Ignition:
CDI (Capacitor Discharge Ignition)
Horsepower Est:
Approx. 45-48 HP (at crank, estimates vary)
Torque Est:
Approx. 30-32 lb-ft (at crank, estimates vary)
Carburetor Model:
Mikuni VM29SS (or similar)
Fuel Type:
Unleaded gasoline (91 octane or higher recommended)
Oil Mixture:
50:1 ratio with high-quality 2-stroke engine oil (e.g., Yamalube 2R or equivalent).
Engine Oil Change:
Periodic inspection and topping up of gearbox oil. Specific intervals for complete fluid flush and replacement will be detailed in the manual.
Air Filter Cleaning:
Recommended after every few rides or as per manual for optimal performance and engine longevity.
Spark Plug Replacement:
Intervals specified for inspection and replacement based on usage and plug condition.
Chain Maintenance:
Regular cleaning, lubrication, and tension adjustment is critical for drivetrain efficiency and lifespan.
Gearbox Oil:
Yamaha recommended gear oil or equivalent API GL-4, SAE 80 or 10W-30 (specific viscosity will be in manual).
Coolant:
Mixture of distilled water and permanent antifreeze (ethylene glycol based), typically 50/50. Specified capacity and type in manual.
Brake Fluid:
DOT 3 or DOT 4 hydraulic brake fluid.
Common Wear Items:
Piston rings, cylinder bore wear, clutch plates, wheel bearings, suspension seals, and fork bushings are common wear items on high-performance 2-stroke motocross bikes of this era.
Ypvs Maintenance:
The Yamaha Power Valve System requires periodic cleaning and proper lubrication to ensure smooth operation and prevent carbon buildup, which can affect performance.
Carburetor Tuning:
Carburetor jetting may need to be adjusted based on altitude, temperature, and modifications to the exhaust or intake systems. Proper tuning is crucial for optimal power and reliability.
Heritage:
Yamaha has a rich history in motorcycle racing, particularly in motocross, with a legacy of innovation and performance dating back to the early days of the sport.
Evolution:
The YZ250 lineage is one of Yamaha's longest-running and most successful motocross lines. The 1995 model represented an evolution in chassis design, suspension technology, and engine tuning from previous generations.
Manufacturing:
Produced by Yamaha Motor Company.
