Yamaha YT175 Tri-Moto, YT175J service manual, 1981-1982 repair guide

Yamaha YT175 Tri-Moto & YT175J Professional Service Manual

Keep your vintage Yamaha 3-wheeler in peak performance with the definitive technical guide used by dealership mechanics. This comprehensive service manual for the Yamaha YT175 series provides professional-grade instructions for everything from routine maintenance to complete engine overhauls. Whether you are a dedicated collector restoring a classic Tri-Moto or an owner performing seasonal tune-ups, this manual delivers the specific technical data required to ensure safety and reliability.

The Yamaha YT175 Tri-Moto is a legendary machine known for its rugged 171cc air-cooled two-stroke engine and 5-speed constant mesh transmission. To maintain the precise "Torque Induction" performance of this vintage ATV, having the correct torque specifications and clearance tolerances is essential.

Models Covered

• Yamaha YT175J Tri-Moto (1981-1982)
• Yamaha YT175 Tri-Moto (1981-1982)

Serial Number Identification

To ensure you are using the correct data for your specific unit, verify your serial numbers:

• Starting Frame Serial Number: 5V7-000101
• Starting Engine Serial Number: 5V7-000101
• Location: The frame number is stamped on the right side of the steering head pipe, and the engine number is located on the right rear section of the engine crankcase.

Comprehensive Technical Coverage

• Engine Overhaul: Detailed procedures for the 171cc two-stroke single, including cylinder honing, piston ring end gap settings (0.30-0.50 mm), and crankshaft runout limits (0.03 mm).
• Autolube System: Critical instructions for the Yamaha Autolube pump (Color Code: Green), including air bleeding procedures and minimum pump stroke adjustments (0.20-0.25 mm) to prevent engine damage.
• Transmission & Clutch: Full teardown and assembly for the 5-speed gearbox and the automatic wet clutch system, including friction plate wear limits (2.1 mm).
• Carburetion: Precise tuning for the Mikuni VM24SS carburetor, featuring float height specs (25mm), main jet (#165), and pilot jet (#40) configurations.
• Chassis & Suspension: Maintenance for the telescopic front forks (116cc oil capacity per leg) and the rear disc brake system with specific wear limits for pads (1.5 mm).
• Electrical System: Troubleshooting for the C.D.I. Magneto, including coil resistance tests (Charge Coil: 300 ohms; Pickup Coil: 10 ohms) and full wiring diagrams.

Why This Manual is Essential

• Clear Utility: Move beyond guesswork with exploded diagrams that show exactly how components fit together, from the crankshaft assembly to the steering head ball races.
• Safety First: Includes critical warnings regarding tire pressure (Standard 2.2 psi) to prevent rim dislodgment and ensure stable handling on varied terrain.
• Professional Specs: Save on expensive shop labor by performing your own repairs with factory-accurate torque settings, such as 30 Nm for cylinder head nuts and 70 Nm for the flywheel magneto.
• Maintenance Schedules: Includes dedicated charts for periodic inspections, lubrication intervals, and cable maintenance to extend the service life of your Tri-Moto.