🏷️ Basic Information

Make:

Yamaha

Model:

Tri-Z 250

Model Code:

YTZ250

Year:

1986

Generation:

First Generation (1985-1987)

👋 Introduction

Market Position:

The Yamaha Tri-Z 250 (YTZ250) was a high-performance, enthusiast-focused three-wheeled ATV (trike) designed for sport riding and off-road recreation. It competed against other sport trikes of the era, offering a powerful two-stroke engine and agile handling.

Competitive Analysis:

Key competitors included models like the Honda TRX250R and the Suzuki LT250R. The Tri-Z was known for its powerful 236cc two-stroke engine, advanced suspension (often featuring a Monoshock rear), and aggressive styling.

Key Features:

Powerful 236cc liquid-cooled two-stroke engine, six-speed transmission, advanced suspension system for superior off-road capability, disc brakes, lightweight chassis, and a focus on performance and rider engagement. The 1986 model year saw refinements over the initial release.

📋 Manual Details

Coverage Areas:

Complete tear down and rebuild, maintenance, troubleshooting, electrical systems, engine, transmission, chassis, suspension, brakes, bodywork, fuel system, ignition system, exhaust system.

Page Count:

146

Manual Type:

Factory Service Manual / Repair Manual

Language:

English

Format:

PDF Download

📖 Manual Coverage

Systems Covered:

Engine (internal components, top-end, bottom-end, cooling, lubrication), Fuel System (carburetor, fuel tank, fuel lines), Ignition System (CDI, magneto, spark plug, ignition timing), Exhaust System (muffler, pipe), Transmission (gearbox, clutch, primary reduction gear, kickstart mechanism), Drivetrain (drive shaft, rear axle, sprocket), Suspension (front forks, rear shock/strut, swingarm), Brakes (front disc, rear drum/disc depending on exact sub-model, master cylinder, calipers, brake lines), Electrical System (wiring harness, lighting, battery, rectifier), Chassis and Frame, Bodywork (panels, fenders, seat, handlebars).

Procedures Included:

Complete disassembly and reassembly, engine overhaul, carburetor tuning and rebuilding (main jet, slow jet, mixture screw adjustments), ignition system testing and repair, suspension adjustments and rebuilds, brake system service, clutch adjustment and replacement, drivetrain maintenance, electrical troubleshooting (no spark issues), fluid changes (engine oil, coolant, brake fluid), component replacement (piston, connecting rod, crankshaft, magneto, stator), frame inspection and repair, routine maintenance schedules.

Technical Depth:

Comprehensive, covering all aspects from routine maintenance and adjustments to complete engine and chassis rebuilds. Includes detailed diagnostic procedures, torque specifications, part diagrams, and troubleshooting guides for various common problems.

📊 Manual Specifications

File Format:

PDF

Print Quality:

High-resolution scans of original factory documentation, ensuring clarity of text and diagrams. Printable without restrictions.

Binding Type:

N/A (Digital Download)

Paper Type:

N/A (Digital Download)

⚙️ Engine Specifications

Primary Engine:

236cc, Liquid-Cooled, Two-Stroke, Reed Valve Induction, Single Cylinder

Bore X Stroke:

65.0 mm x 70.0 mm

Compression Ratio:

6.6:1 (approximate, varies by specific model/tuning)

Horsepower:

Approximately 25-30 HP (est. from period reviews and similar engines)

Carburetor:

Mikuni VM34SS (likely a 34mm slide carburetor with pilot jet and main jet)

Fuel Type:

Unleaded gasoline with 2-stroke oil mixture (pre-mix or oil injection, typically 50:1 ratio)

Fuel Tank Capacity:

Approximately 3.0 gallons (11.4 Liters)

Cooling Method:

Liquid-Cooled

Engine Oil Type:

2-stroke specific engine oil (premix or oil injection system)

🔧 Transmission

Transmission Type:

6-Speed Constant Mesh

Clutch Type:

Wet, Multi-Plate

Drive Type:

Chain Drive

Primary Reduction Gear:

Included in drivetrain specifications

📐 Dimensions

Overall Length:

Approximately 72.6 inches (1845 mm)

Overall Width:

Approximately 46.1 inches (1170 mm)

Overall Height:

Approximately 43.1 inches (1095 mm)

Dry Weight:

Approximately 348 lbs (158 kg)

Wheelbase:

Approximately 49.6 inches (1260 mm)

Ground Clearance:

Approximately 6.3 inches (160 mm)

🛡️ Safety Features

Safety Ratings:

Not applicable for off-road vehicles of this era in the same manner as passenger cars. Focus on rider skill and responsible operation.

Active Features:

Disc brakes (front and rear), stable chassis geometry.

Passive Features:

Handlebar padding, comfortable seating position.

💡 Technology Features

Infotainment System:

N/A (Basic recreational vehicle, no infotainment features).

Driver Assistance Features:

N/A (Basic mechanical controls, no electronic driver assistance).

Connectivity Features:

N/A (No electronic connectivity features).

🔧 Maintenance

Service Intervals:

The manual provides detailed recommended service intervals for engine oil changes (pre-mix ratio), spark plug inspection/replacement, air filter cleaning/replacement, chain lubrication/adjustment, brake fluid checks, coolant checks, and general chassis lubrication. Specific intervals will be outlined within the manual, typically based on operating hours or mileage.

Engine Oil Specification:

Yamaha recommends a high-quality 2-stroke oil for pre-mix or the oil injection system, typically at a 50:1 ratio (oil to fuel). Specific Yamaha branded oils or equivalent JASO FD rated oils are advisable.

Coolant Type:

Ethylene glycol based permanent type coolant (e.g., Yamaha Yamalube Coolant or equivalent anti-freeze/anti-corrosion mixture).

Brake Fluid Type:

DOT 3 or DOT 4 hydraulic brake fluid.

Known Issues:

Common issues for vintage two-stroke ATVs like the Tri-Z can include carburetor gumming due to fuel degradation, ignition system component failure (CDI, stator, coil), wear on suspension bushings and bearings, clutch wear, and potential crank seal leaks leading to air leaks. Overheating due to coolant system issues or improper jetting can also occur. The manual addresses troubleshooting for these and many other potential problems.

📚 Vehicle History

Brand Heritage:

Yamaha Motor Company has a long and distinguished history in powersports, known for innovation, performance, and reliability across motorcycles, ATVs, personal watercraft, and more. The Tri-Z falls within their early and influential ATV lineup.

Model Evolution:

The Tri-Z 250 was introduced in 1985, featuring a powerful two-stroke engine and advanced suspension. The 1986 model year brought various updates and refinements, often including improved suspension components, minor styling tweaks, and potentially engine tuning adjustments to enhance performance or reliability. It was succeeded by the Banshee (two-stroke twin-cylinder) and Warrior (four-stroke single-cylinder) in Yamaha's ATV lineup.

Production Years:

1985-1987

🏆 Awards & Recognition

Recognitions:

While specific awards for the 1986 Tri-Z may not be widely documented in a consumer sense, it was recognized by enthusiasts and media of the era as a formidable and exciting sport ATV. Its performance and handling capabilities were highly regarded.