Market Segment:
Motocross / Off-road competition bike, a significant player in the 250cc two-stroke class during its era.
Key Competitors:
Honda CR250R, Suzuki RM250, Kawasaki KX250.
Performance Focus:
Renowned for its potent engine and agile handling, making it a favorite for motocross riders seeking aggressive performance.
Yz Lineage:
Part of Yamaha's esteemed YZ series, known for continuous innovation and racing success.
General Coverage:
Comprehensive service, repair, and workshop information for the 1994 Yamaha YZ250.
Model Year Coverage:
Primary focus on 1994 Yamaha YZ250. States compatibility with similar years and models.
Estimated Page Count:
Refer to specific product listing for exact page count, typically 300-500 pages for this era/type of manual.
Manual Type:
Service Repair Workshop Manual
Language:
English (standard for official Yamaha service manuals of this era)
Format:
Likely a digital format (PDF) for modern sales, but historically printed.
Engine System:
Detailed disassembly, assembly, inspection, diagnosis, and repair of the 249cc 2-stroke engine, including carburetor, ignition, cooling, and lubrication systems.
Transmission System:
Coverage of the gearbox, clutch operation, shifting mechanisms, and associated components.
Chassis And Suspension:
Front and rear suspension (forks, shock absorber, linkages), steering, frame components, and swingarm.
Braking System:
Front and rear brake systems (hydraulic disc brakes), including caliper, master cylinder, and fluid maintenance.
Electrical System:
Ignition system (CDI, spark plug), lighting, wiring diagrams, and troubleshooting of electrical faults.
Fuel System:
Fuel tank, petcock, fuel lines, and detailed carburetor tuning and rebuilding procedures (likely for Mikuni VM series).
Bodywork And Trim:
Removal and installation of body panels, seat, fenders, and handlebars.
Routine Maintenance:
Oil changes, filter cleaning/replacement, spark plug replacement, chain adjustment, air filter service.
Engine Repair:
Top-end rebuild (piston, rings, cylinder), crankshaft and bearing service, complete engine disassembly and reassembly.
Carburetor Overhaul:
Detailed steps for cleaning, rebuilding, and jetting the carburetor for optimal performance.
Suspension Service:
Fork seal replacement, fork oil changes, shock absorber servicing, and linkage lubrication.
Troubleshooting:
Diagnostic charts and procedures for identifying and resolving common issues, including starting problems, poor performance, and electrical faults.
Wiring Diagrams:
Complete electrical schematics for easier diagnosis of electrical system issues.
Depth Of Coverage:
Highly detailed, suitable for professional technicians and experienced DIY mechanics. Includes specifications, tolerances, and torque values for all components.
Engine Displacement:
249cc
Engine Configuration:
Single-cylinder, liquid-cooled, reed valve induction, 2-stroke
Bore X Stroke:
68.0 mm x 68.5 mm
Compression Ratio:
8.4:1 (nominal)
Ignition System:
CDI (Capacitor Discharge Ignition)
Carburetor:
Likely a Mikuni VM36 (36mm) flat-slide carburetor. Specific jetting and settings are detailed in the manual.
Horsepower Estimate:
Approx. 45-48 HP (at the crank, estimated for the era)
Torque Estimate:
Approx. 30-32 lb-ft (at the crank, estimated for the era)
Fuel Type:
Unleaded gasoline mixed with 2-stroke oil (typical ratio 50:1 or as specified in manual).
Fuel Tank Capacity:
Typically around 2.4 - 2.8 US gallons (9.0 - 10.5 Liters).
Premix Ratio:
50:1 (Yamalube 2R or equivalent premium 2-stroke oil) is a common recommendation.
Overall Length:
Varies, but typically around 2150 mm (84.6 in)
Overall Width:
Varies, but typically around 800 mm (31.5 in)
Overall Height:
Varies, but typically around 1200 mm (47.2 in)
Dry Weight:
Approx. 216 lbs (98 kg)
Wet Weight:
Approx. 230-240 lbs (104-109 kg) with fluids
Ground Clearance:
Typically around 13 inches (330 mm)
Air Filter Cleaning:
After every few rides, or more frequently in dusty conditions. Manual will specify exact interval and cleaning procedure.
Spark Plug Inspection:
Regularly check for fouling and wear. Replacement interval depends on usage and plug type.
Chain Lubrication And Adjustment:
After every ride, or as needed based on play. Manual specifies correct tension.
Top End Rebuild:
Highly dependent on usage intensity, but typically recommended every 30-60 hours of racing or intensive use.
Suspension Service:
Fork oil changes and seal inspection typically every 20-30 hours. Linkage lubrication annually or more often.
Engine Oil Type:
Premium 2-stroke engine oil (e.g., Yamalube 2R, Motul 800, or similar JASO FD certified).
Transmission Oil Type:
Yamaha Motorcycle Gear Oil (or equivalent SAE 10W-30 API SE, SF, SG, SH, SJ classification).
Coolant Type:
Permanent type antifreeze (ethylene glycol based) mixed with distilled water at a 50:50 ratio.
Brake Fluid Type:
DOT 3 or DOT 4 hydraulic brake fluid.
Power Valve Sticking:
Common on older 2-strokes, can lead to poor performance. Requires regular cleaning and lubrication. Manual details this procedure.
Carburetor Tuning:
Sensitive to altitude and temperature changes. Proper jetting and cleaning are crucial for optimal running. Manual provides detailed guidance.
Suspension Wear:
Wear items like seals, bushings, and oil will degrade over time, impacting ride quality and control. Routine servicing is essential.
Yamaha Motorsports:
Yamaha has a long and successful history in motorsports, particularly in motocross, with the YZ line being a cornerstone.
Yz250 Development:
The 1994 model represents an evolution of Yamaha's highly competitive 250cc two-stroke motocross platform, building on previous generations with refinements in engine power, suspension, and chassis design.
Production Era:
The YZ250 two-stroke was produced for many years, with the mid-90s being a period of intense development and competition.
Motocross Magazine Awards:
While specific awards for the 1994 model might not be readily available, the YZ250 line consistently received praise and 'bike of the year' awards from major dirt bike publications throughout its production history for its performance and innovation.
Rider Satisfaction:
High rider satisfaction due to its competitive performance and the inherent fun factor of a potent 2-stroke engine.
