The Tri-Z 250, model code YTZ250, specifically the YTZ250N variant, was a formidable sport ATV produced in 1985 and the subsequent 1985.5 model year. Designed for high-performance recreational riding, particularly in challenging off-road environments like sand dunes, the Tri-Z 250 distinguished itself with its powerful 246cc liquid-cooled two-stroke engine, advanced long-travel suspension, and effective disc brake systems. Its engineering emphasized agility and power, making it a competitive and exciting choice in the sport ATV market of its era, building on an established reputation for performance and innovation in powersports. This comprehensive 137-page English-language manual serves as an indispensable resource for the maintenance, repair, and understanding of the Tri-Z 250. It covers all critical systems, including detailed engine overhaul procedures, transmission maintenance, chassis and suspension adjustments, brake system servicing, and electrical system troubleshooting. The manual provides routine maintenance schedules, step-by-step repair instructions, diagnostic guidance, and factory specifications essential for both owners and professional technicians. Its clear illustrations and detailed explanations ensure that owners and mechanics can effectively maintain and restore the Tri-Z 250 to optimal working condition. 🏷️ Basic Information Identification Make: Yamaha Model: Tri-Z 250 Model Code: YTZ250 Model Variant: YTZ250N Year: 1985 / 1985.5 👋 Introduction Market Position Market Position: The Yamaha Tri-Z 250 was a high-performance, specialized three-wheeler ATV designed for sport riding, particularly in sand dune environments. It occupied a niche but significant segment of the ATV market in the mid-1980s. Competitive Analysis Competitive Analysis: Competed against other performance ATVs of the era, including models from Honda (like the ATC250R) and Suzuki. The Tri-Z was known for its powerful engine and aggressive styling. Key Features Key Features Of Vehicle: Powerful 246cc liquid-cooled 2-stroke engine, long-travel suspension, disc brakes, and a reputation for being a capable and exciting sport ATV. Key Features Of Manual Key Features Of Manual: Detailed illustrations, clear step-by-step instructions, troubleshooting assistance, factory specifications, used by professional technicians, DIY friendly. 📋 Manual Details Coverage Areas Vehicle Covered: Yamaha Tri-Z 250 YTZ250 (1985-1985.5) Page Count Page Count: 137 Manual Type Manual Type: Repair and Service Manual / Workshop Manual / Factory Manual Language Language: English Format Format: PDF Download 📖 Manual Coverage Systems Covered Engine: Complete engine overhaul, diagnosis, performance tuning, carburetor adjustment, fuel system, lubrication, ignition system, cooling system (radiator, coolant), exhaust system (muffler). Transmission: Gearbox, primary reduction gear, clutch, transmission fluid, gear shifting mechanisms. Chassis And Suspension: Frame, front forks, rear suspension (struts, swingarm, linkage), steering system, wheels, tires. Brakes: Front and rear brake systems, brake fluid, brake pads, rotors, hydraulic system. Electrical System Electrical System: Ignition system (magneto, coil, plug), starting system (kickstart, starter), lighting, switches, battery, rectifier, wiring diagrams, troubleshooting electrical problems (no spark). Bodywork And Plastics Bodywork And Plastics: Panels, fenders, seat, handlebars, plastics. Procedures Included Maintenance: Routine maintenance, preventative maintenance schedules, fluid changes, filter replacements, lubrication points. Repair And Rebuild: Detailed step-by-step instructions for repairing, rebuilding, and restoring all major components. Troubleshooting: Comprehensive troubleshooting guides for diagnosing and resolving common and uncommon problems. Diagnostics: Diagnostic procedures for identifying the root cause of issues. Technical Depth Technical Depth: Complete coverage from basic adjustments to full engine rebuilds and complex electrical system diagnosis. 📊 Manual Specifications File Format File Format: PDF File Compatibility: Windows, Linux, Mac OS File Enhancement: Requires WinZip or WinRAR for unzipping if compressed. Print Quality Print Quality: Printable on any computer Binding Type Binding Type: Digital Download (No physical copy) Paper Type Paper Type: N/A (Digital) ⚙️ Engine Specifications Primary Engine Engine Type: 2-stroke, liquid-cooled Displacement: 239cc (actual displacement often cited as 243cc or 246cc depending on source and tuning) Bore X Stroke: 68.0 mm x 64.0 mm Compression Ratio: 6.7:1 (typical for this era, can vary slightly) Carburetor: Single Mikuni VM34SS (often cited as 34mm) Performance Horsepower: Approximately 24-26 HP (at the crankshaft, estimations vary) Torque: Not explicitly stated in common documentation, but significant for its class. Fuel System Fuel Type: Unleaded gasoline with 2-stroke oil mixture (pre-mix) Oil Viscosity Recommendation: 2-stroke specific oil (Yamaha recommends Yamalube 2, SAE 10W-30 or 20W-40 for general use, consult manual for specifics). Engine Components Cylinder: Single cylinder Crankshaft: Forged crankshaft Connecting Rod: Conrod Valves: Reed valve induction Camshaft: N/A (2-stroke engines typically do not have camshafts in the traditional sense; rely on reed valves). Ignition Ignition System: CDI (Capacitor Discharge Ignition) Magneto: Internal magneto ignition 🔧 Transmission Standard Transmission Type: 6-speed constant mesh Clutch Type: Wet multi-plate Drive Train: Chain drive Gear Ratios: Specific gear ratios are detailed within the manual. Features Gearshift: Heel-toe shift lever 📐 Dimensions Weights Dry Weight: Approximately 150 kg (330 lbs) Fuel Tank Capacity: Approximately 10 liters (2.6 US gallons) Oil Tank Capacity: Approximately 1.5 liters (0.4 US gallons) Cooling System Capacity: Approximately 1.3 liters (1.4 US quarts) 🔧 Maintenance Service Intervals Engine Oil Change Interval: Refer to manual for specific transmission oil change intervals...