1986 Yamaha TT350 Service Manual

The 1986 Yamaha TT350 is a dual-sport motorcycle featuring a 349cc air-cooled four-stroke single-cylinder engine, 5-speed transmission, electric start, front disc brake, rear drum brake, and dual-purpose tires. This service manual covers maintenance procedures, specifications, troubleshooting, and repair instructions for proper servicing and operation of the motorcycle.

1. General Information 2. Specifications 3. Periodic Maintenance 4. Engine 5. Cooling System 6. Fuel System 7. Electrical System 8. Chassis 9. Troubleshooting 10. Wiring Diagrams 11. Torque Specifications

General Information

This manual provides detailed service information for the 1986 Yamaha TT350. Includes identification numbers, general precautions, and special tools required for maintenance.

ComponentLocation
Frame serial numberRight side of steering head
Engine serial numberLeft side of crankcase
Model designationTT350G
Manufacture dateStamped on steering head

Specifications

Periodic Maintenance

Regular maintenance schedule for optimal performance and longevity.

Service ItemEvery 1000kmEvery 3000kmEvery 6000km
Engine oil change✓
Oil filter cleaning✓
Spark plug inspection✓
Air filter cleaning✓
Valve clearance check✓
Brake system inspection✓
Chain adjustment✓

Engine

Complete engine service procedures including disassembly, inspection, and reassembly.

  1. Cylinder Head Removal: Drain coolant, remove cam chain tensioner, disconnect cables.
  2. Valve Adjustment: Set piston at TDC compression, adjust intake: 0.10-0.15mm, exhaust: 0.15-0.20mm.
  3. Piston/Cylinder: Inspect for wear, measure cylinder bore, check ring end gap.
  4. Crankshaft/Connecting Rod: Check big end play, rod small end play.
  5. Clutch: Adjust cable free play 10-15mm at lever.

WARNING! Always use new gaskets during reassembly. Torque bolts to specification.

Cooling System

The TT350 features air cooling with oil cooler. Maintenance includes fin cleaning and oil cooler inspection.

Fuel System

Carburetor service and fuel system maintenance procedures.

  1. Carburetor Removal: Disconnect fuel line, throttle cables, and vent lines.
  2. Float Level: Set to 18.5mm ± 1.0mm
  3. Main Jet: #130 (standard)
  4. Pilot Jet: #42.5 (standard)
  5. Needle Clip Position: 3rd groove from top
  6. Fuel Filter: Clean or replace every 6000km

Electrical System

Complete electrical system service including charging, ignition, and lighting systems.

ComponentSpecification
Battery12V 8Ah
Alternator output14V 15A at 5000 rpm
Spark plugNGK DR8ES or ND X24ES-U
Plug gap0.6-0.7mm
Headlight12V 35/35W
Tail light12V 5/21W

Chassis

Frame, suspension, brakes, and wheels service procedures.

  1. Front Fork: Oil capacity 335ml per leg, oil type 10W
  2. Rear Shock: Check for oil leaks, adjust preload as needed
  3. Wheel Bearings: Inspect for play every 3000km
  4. Brake Pads: Replace when worn to 1.0mm thickness
  5. Chain: Adjust slack to 45-55mm
  6. Tire Pressure: Front 1.5 kg/cm², Rear 1.8 kg/cm²

Troubleshooting

ProblemPossible CauseSolution
Hard startingWeak battery, dirty carburetor, valve clearanceCharge battery, clean carb, adjust valves
Poor performanceClogged air filter, worn spark plugClean air filter, replace spark plug
OverheatingLow oil, dirty cooling fins, lean mixtureCheck oil level, clean fins, adjust carb
Electrical failureBlown fuse, bad connectionCheck fuses, clean connections
Brake dragStuck caliper, contaminated fluidClean caliper, replace brake fluid

Wiring Diagrams

Complete electrical wiring diagrams for the 1986 Yamaha TT350. Includes color-coded wires and connector locations.

NOTE: Always disconnect battery before working on electrical system.

Torque Specifications

ComponentTorque Value
Cylinder head nuts30 Nm
Spark plug12 Nm
Engine mounting bolts55 Nm
Front axle nut65 Nm
Rear axle nut90 Nm
Sprocket nuts25 Nm
Oil drain plug25 Nm
Front brake caliper bolts25 Nm
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