This manual covers the Tri-Z 250, produced from 1985 to 1986. Model codes include YZ250-R for 1985 and YZ250-S for 1986. The Tri-Z 250 is a liquid-cooled, 2-stroke, 239cc three-wheel ATV, known for its performance and agility, drawing on extensive experience in motocross and racing. It features a 6-speed constant mesh transmission with a wet, multi-plate clutch and disc brakes for active safety. While specific horsepower figures vary, it typically produced around 36-40 HP. This model represents development in the three-wheel ATV market, building upon its heritage in high-performance off-road vehicles. This factory service repair manual provides comprehensive information for the Tri-Z 250 (1985-1986). It details complete engine overhaul, transmission and clutch service, brake system maintenance, electrical system diagnostics including wiring diagrams, suspension servicing, fuel system repairs, and chassis work. The manual also includes general maintenance procedures, troubleshooting guides for common issues, lubrication schedules, and technical data sheets with specifications and tolerances. It is designed for technicians, mechanics, and owners, offering factory-level repair and diagnostic information to ensure the proper maintenance and repair of the vehicle. 🏷️ Basic Information Identification Make: Yamaha Model: Tri-Z 250 Year: 1985-1986 Codes Model Code: YZ250-R (1985), YZ250-S (1986) 👋 Introduction Market Position Target Audience: Technicians, mechanics, and owners for repair and learning Competitive Analysis Value Proposition: Low price, great quality, instant access, direct support Key Features Feature 1: Complete factory information matching original manufacturer books Feature 2: Detailed circuits and diagrams included Feature 3: Suitable for both professional repair and self-learning 📋 Manual Details Coverage Areas Primary Coverage: Service and Repair Secondary Coverage: Maintenance, Troubleshooting, Technical Data, Diagrams Page Count Estimated Page Count: Hundreds or Thousands (Printable Pages) Manual Type Type: Official Factory Service Repair Manual Language Language: English Format File Format: PDF Compression Requirement: WinZip (for larger manuals) 📖 Manual Coverage Systems Covered Engine Service: Complete engine overhaul, rebuild, and tuning Transmission Service: Gearbox inspection, repair, and clutch service Brake System: Hydraulic brake system service, fluid replacement, caliper and master cylinder repair Electrical System: Wiring diagrams, component testing, lighting, ignition system Suspension: Front and rear suspension inspection, fork seals, shock absorber service Fuel System: Carburetor service and tuning, fuel tank, fuel lines Cooling System: Radiator, coolant, water pump inspection and service Steering: Steering mechanism inspection and adjustment Chassis Bodywork: Frame inspection, body panel repair and alignment Wheel Drive: Chain drive, sprockets, rear axle inspection Procedures Included General Maintenance: Scheduled maintenance, pre-ride checks, cleaning Troubleshooting: Diagnostic procedures for common problems and symptoms Repair Procedures: Step-by-step instructions for component replacement and repair Lubrication: Periodic lubrication points and schedules Wiring Diagrams: Detailed electrical schematics for all systems Technical Data Sheets: Specifications, tolerances, and measurements Technical Depth Depth: Comprehensive factory-level repair and diagnostic information 📊 Manual Specifications File Format Compatibility: All Versions of Windows & Mac Print Quality Quality: Great Quality (Printable) Binding Type Binding: Digital Download (Not Applicable) Paper Type Paper Type: Digital Download (Not Applicable) Delivery Method: Instant Download Requirements Software Requirements: Adobe PDF Reader ⚙️ Engine Specifications Primary Engine Engine Type: Liquid-cooled, 2-stroke, reed valve Displacement: 239cc (approximate) Performance Horsepower: Approximately 36-40 HP (depending on year and tuning) Torque: Specific torque figures vary by year, detailed in manual Fuel System Carburetor: Mikuni VM34SS (typical) Fuel Type: Unleaded gasoline with 2-stroke oil mixture Cooling System Cooling Method: Liquid-cooled 🔧 Transmission Standard Transmission Type: 6-speed constant mesh Optional Optional Gearbox: N/A Features Clutch: Wet, multi-plate Fluid Requirements Transmission Oil: Yamalube or equivalent 10W-30, 10W-40, or 20W-40 API SE type (specifics in manual) 📐 Dimensions Exterior Wheelbase: Refer to manual for exact dimensions (typically around 54 inches) Weights Dry Weight: Approximately 258 lbs (117 kg) 🛡️ Safety Features Ratings Safety Ratings: Not applicable for this type of vehicle in modern standards Active Features Active Safety: Disc brakes (front and rear) Passive Features Passive Safety: Sturdy frame construction 💡 Technology Features Infotainment Infotainment Features: N/A (basic mechanical vehicle) Driver Assistance Driver Assistance Systems: N/A Connectivity Connectivity Options: N/A 🔧 Maintenance Service Intervals Oil Change Interval: Refer to manual for specific hours/miles, typically every few months or based on usage Spark Plug Replacement: Recommended every few thousand miles or as needed based on condition Fluid Specifications Coolant Type: Ethylene glycol-based antifreeze (50/50 mix with distilled water) Brake Fluid Type: DOT 3 or DOT 4 brake fluid Known Issues Common Issues: Carburetor tuning, suspension seal leaks, occasional electrical gremlins, exhaust carbon buildup Recommended Tools Special Tools: Various metric wrenches, sockets, torque wrench, specialized engine tools (detailed in manual) 📚 Vehicle History Brand Heritage Heritage: Yamaha's legacy in high-performance off-road and racing motorcycles Model Evolution Tri Z Development: Developed as a competitor in the emerging 3-wheel ATV market, building on YZ motocross technology Production Production Period: 1985-1986 🏆 Awards & Recognition Recognitions Historical Recognition: Popular in its era for performance and agility in the 3-wheel ATV segment.