1986 Yamaha XT350 Service Manual

The 1986 Yamaha XT350 is a dual-sport motorcycle featuring a 346cc air-cooled four-stroke single-cylinder engine, 6-speed transmission, 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 upkeep of your XT350.

1. General Information 2. Periodic Maintenance 3. Engine Service 4. Fuel System 5. Electrical System 6. Chassis & Suspension 7. Brake System 8. Troubleshooting 9. Specifications 10. Wiring Diagrams

General Information

Introduction to the Yamaha XT350 model and service manual organization.

Component	Description
Model Identification	XT350K (1986 model year)
Frame Type	Steel semi-double cradle
Overall Length	85.4 inches (2170mm)
Overall Width	33.5 inches (850mm)
Overall Height	48.8 inches (1240mm)
Wheelbase	56.7 inches (1440mm)
Ground Clearance	10.6 inches (270mm)
Seat Height	34.6 inches (880mm)
Dry Weight	262 lbs (119kg)
Fuel Capacity	2.6 gallons (10 liters)

Periodic Maintenance

Regular maintenance schedule and procedures for optimal performance.

Oil Change: Every 3,000 miles or 6 months - Use SAE 10W-40 motorcycle oil
Oil Filter: Replace every other oil change
Air Filter: Clean every 600 miles, replace as needed
Spark Plug: Check/adjust every 3,000 miles, replace every 6,000 miles
Valve Clearance: Check every 3,000 miles
Chain Adjustment: Every 600 miles
Brake Inspection: Check pads/shoes every 1,500 miles

WARNING! Always use proper safety equipment and follow torque specifications. Engine must be cool before servicing.

Engine Service

Engine disassembly, inspection, and reassembly procedures.

Cylinder Head Removal: Remove tank, carburetor, then cylinder head bolts in crisscross pattern
Valve Adjustment: Intake 0.10-0.15mm, Exhaust 0.15-0.20mm
Piston/Cylinder: Standard bore 84mm, oversizes available
Cam Chain: Check tensioner and chain wear
Clutch: Fiber and metal plate inspection/replacement
Transmission: Gear inspection and shift mechanism service

CAUTION! Mark all components during disassembly. Use new gaskets during reassembly.

Fuel System

Carburetor: Mikuni BST34SS constant velocity type
Main Jet: #135 standard
Pilot Jet: #42.5 standard
Float Height: 21.5mm
Fuel Cock: Vacuum operated with reserve position
Air Filter: Foam element, clean with solvent and re-oil
Throttle Cable: Check for smooth operation and proper free play

Electrical System

Battery, charging system, ignition, and lighting maintenance.

Battery: 12V 10Ah, maintain fluid level, specific gravity 1.280

Charging System: AC magneto with rectifier/regulator, output 14V 15A at 5000 RPM

Ignition: CDI electronic ignition, timing fixed, spark plug NGK DR8ES or equivalent

Lighting: Headlight 60/55W, brake/tail 21/5W, turn signals 21W

Chassis & Suspension

Frame, wheels, tires, and suspension component service.

Front Fork: Oil capacity 435cc per leg, oil weight SAE 10W
Rear Shock: Spring preload adjustable, check for oil leaks
Wheel Bearings: Check for play and smooth rotation
Tire Pressure: Front 21 psi, Rear 25 psi (street use)
Steering Head: Adjust bearing play, lubricate regularly

Tip: Always use proper wheel alignment tools when servicing wheels.

Brake System

Front disc brake and rear drum brake maintenance procedures.

Front Brake: Single piston caliper, disc thickness 4.0mm (min 3.5mm)
Brake Pads: Replace when worn to 1.0mm thickness
Brake Fluid: DOT 4, change every 2 years
Rear Brake: Drum type, adjust cable for proper free play
Brake Shoes: Replace when worn to minimum thickness
Brake Lever: Adjust for proper reach and free play

WARNING! Never use petroleum-based products on brake components. Always bleed brakes properly.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Hard starting	Fuel delivery, spark, compression	Check fuel flow, spark plug, valve clearance
Poor performance	Clogged air filter, carb issues	Clean air filter, check jetting, adjust carb
Electrical failure	Battery, stator, regulator	Test charging system components
Oil consumption	Worn rings, valve seals	Compression test, inspect cylinder
Transmission issues	Worn gears, shift mechanism	Inspect transmission components

Specifications

Complete technical specifications for the 1986 Yamaha XT350.

Engine Type: 4-stroke, air-cooled, SOHC, 2-valve single
Displacement: 346cc
Bore x Stroke: 84.0 x 62.5mm
Compression Ratio: 8.3:1
Carburetion: Mikuni BST34SS
Ignition: CDI electronic
Transmission: 6-speed constant mesh
Final Drive: Chain
Front Suspension: Telescopic fork, 8.7" travel
Rear Suspension: Swingarm with single shock, 7.9" travel
Front Tire: 3.00-21
Rear Tire: 4.60-18
Front Brake: Hydraulic disc
Rear Brake: Mechanical drum

Wiring Diagrams

Complete electrical wiring schematics for troubleshooting electrical issues.

Color-coded diagrams showing main harness, lighting circuits, ignition system, and charging system. Includes connector locations and ground points.

CAUTION! Disconnect battery before performing electrical work. Use multimeter for proper diagnosis.