Market Segment:
High-performance sport ATV, catering to recreational riders and racers in the mid-80s era.
Competitors:
Competed against models like the Honda TRX250R, Suzuki LT250R, and Kawasaki Tecate-4.
Distinctive Features:
Known for its powerful 2-stroke engine, advanced suspension for its time, lightweight design, and sporty handling. A benchmark in early sport ATVs.
Systems Covered:
Engine, Chassis, Electrical Systems, Regular Maintenance, Troubleshooting
Estimated Page Count:
Refer to specific manual for exact count; typically 200-400 pages for comprehensive factory service manuals.
Manual Type:
Factory Service Manual / Repair Manual
File Format:
PDF Download
Engine Systems:
Top-end (cylinder, piston, rings), bottom-end (crankshaft, connecting rod, bearings), carburetor, cooling system, ignition system, exhaust system, lubrication system, engine disassembly and reassembly procedures.
Chassis Systems:
Frame, suspension (front and rear), steering system, wheels, tires, brakes (front and rear), drivetrain (chain, sprockets), swingarm, shock absorbers, linkage systems.
Electrical Systems:
Wiring diagrams, lighting system, ignition system components, battery, charging system, fuses, electrical troubleshooting guides, component testing.
Maintenance Procedures:
Regular lubrication, filter changes (air, oil - if applicable), chain adjustment, spark plug replacement, brake adjustments, carburetor adjustments, valve clearance checks (if applicable), tire pressure checks.
Repair Procedures:
Engine overhaul, transmission repair, carburetor rebuilding, suspension component replacement, brake caliper service, electrical component replacement, frame repair (minor).
Troubleshooting Procedures:
Step-by-step diagnostic procedures for common problems, identification of symptoms, testing of electrical and mechanical components, carburetor tuning issues, starting problems, performance issues.
Depth Of Coverage:
Comprehensive, covering from basic scheduled maintenance and adjustments to complete engine and chassis overhauls, including detailed diagnostic troubleshooting for all major systems.
Engine Type:
2-stroke, single-cylinder, reed valve induction
Displacement:
236cc (236 cm³)
Bore X Stroke:
67.0 mm x 68.0 mm
Cooling System:
Liquid-cooled
Compression Ratio:
6.7:1 (Typical)
Horsepower Approximate:
Approximately 25-30 HP (at crankshaft, varies by tuning and specific variant)
Carburetor Type:
Mikuni VM26SS (or similar, typically single carb)
Fuel Type:
Unleaded gasoline with 2-stroke oil premix
Premix Ratio:
Typically 20:1 or 25:1 (check specific manual for exact recommendation)
Transmission Type:
6-speed constant mesh, semi-automatic clutch (manual operated)
Drive System:
O-ring sealed chain drive to rear wheels
Clutch Type:
Wet, multi-plate, manual operation
Overall Length:
Approximately 1850 mm (72.8 in)
Overall Width:
Approximately 775 mm (30.5 in)
Overall Height:
Approximately 1075 mm (42.3 in)
Dry Weight:
Approximately 150 kg (331 lbs)
Fuel Tank Capacity:
Approximately 10 Liters (2.6 US gal)
Safety Standards:
ATV safety standards of the era; emphasis on rider skill and proper riding gear. No formal crash ratings as with modern vehicles.
Braking System:
Hydraulic disc brakes front and rear for superior stopping power compared to drum brakes of earlier models.
Suspension System:
Long-travel independent front suspension (or A-arm) and mono-shock rear suspension with linkage for improved handling and rider comfort over rough terrain.
Rider Ergonomics:
Designed for an aggressive riding posture, with handlebar positioning and footpeg placement optimized for sport riding.
Oil Change Interval Engine:
Refer to manual; typically every 20-30 engine hours or annually. For premix 2-strokes, focus is on regular rebuilds and top-end checks.
Air Filter Maintenance:
Frequent cleaning and inspection recommended, especially in dusty conditions. Refer to manual for specific cleaning procedures (e.g., washing, re-oiling).
Chain Lubrication Adjustment:
Lubricate chain after every ride or every few hours of use, and check tension regularly as per manual guidelines. Chain wear is critical.
Coolant Type:
Ethylene glycol-based antifreeze mixed with distilled water (50/50 ratio recommended). Specific capacity found in manual.
Transmission Oil Type:
Yamaha recommends specific 2-stroke oil for premix, and SAE 10W-30 or SAE 10W-40 motorcycle gear oil for the transmission/clutch, though this is often integrated with premix for 2-strokes, or a separate gearbox.
Common Wear Items:
Piston rings, cylinder wear, clutch plates, wheel bearings, suspension bushings, carburetor jets, exhaust packing (if applicable).
Electrical Gremlins:
Wire harness degradation, CDI unit issues, stator or lighting coil failures are possible with age.
Carburetor Problems:
Clogged jets, float bowl issues, vacuum leaks leading to poor idling, throttle response, or overall power.
Yamaha Atv Legacy:
Yamaha has a long and storied history in ATV manufacturing, pioneering many innovations and building a reputation for performance and reliability.
Tri Z Introduction:
The Tri-Z 250 was a significant model in Yamaha's ATV lineup, marking a strong entry into the sport ATV segment with its potent engine and advanced chassis.
Production Period:
Produced from 1985 to 1988. This manual specifically covers the 1984 model year, which was the initial release or a very early iteration.
