1987 Yamaha Warrior Service Manual

The 1987 Yamaha Warrior is a high-performance ATV featuring a 348cc four-stroke engine, 5-speed transmission with reverse, shaft drive system, independent rear suspension, and rugged off-road capabilities. This service manual provides comprehensive technical information for maintenance, repair, and troubleshooting procedures. Below are key sections covering specifications, maintenance schedules, engine service, transmission, electrical systems, and troubleshooting.

General Information

Key components: 348cc SOHC 4-stroke engine, 5-speed manual transmission with reverse, shaft final drive, independent rear suspension, front and rear hydraulic disc brakes.

Specifications

• Engine: 348cc, 4-stroke, SOHC, air-cooled single cylinder
• Bore x Stroke: 83.0 x 64.5 mm
• Compression Ratio: 9.2:1
• Carburetor: Mikuni BS34SS
• Ignition System: CDI
• Starting System: Electric and kick start
• Transmission: 5-speed constant mesh with reverse
• Final Drive: Shaft
• Suspension Front: Double A-arm with hydraulic shocks
• Suspension Rear: Independent with hydraulic shocks
• Brakes: Hydraulic disc front and rear
• Tires Front: 22x7-10
• Tires Rear: 22x10-10
• Fuel Capacity: 2.6 gallons (10 liters)

Periodic Maintenance

Regular maintenance ensures optimal performance and longevity.

1. Daily: Check fuel level, tire pressure, brake operation
2. Every 100 miles: Check engine oil level, chain tension, brake pads
3. Every 500 miles: Change engine oil and filter, inspect spark plug
4. Every 1000 miles: Clean air filter, check valve clearance, inspect brakes
5. Every 2000 miles: Change final drive oil, inspect suspension components

WARNING! Always perform maintenance on level ground with engine off and cool. Use proper safety equipment.

Engine Service

Engine removal, disassembly, inspection, and reassembly procedures.

1. Engine Removal: Disconnect battery, drain fluids, remove exhaust, disconnect wiring and cables
2. Cylinder Head: Remove camshaft, inspect valves and seats, check compression
3. Cylinder & Piston: Measure cylinder bore, inspect piston and rings
4. Crankshaft & Connecting Rod: Check bearing clearance, inspect crankpin
5. Lubrication System: Clean oil passages, check oil pump
6. Cooling System: Clean cooling fins, check for debris

Torque Specifications: Cylinder head bolts: 30 ft-lb, Spark plug: 18 ft-lb, Oil drain plug: 22 ft-lb

Fuel System

Carburetor service and fuel delivery system maintenance.

1. Carburetor Removal: Disconnect fuel line, throttle cable, and vent lines
2. Carburetor Disassembly: Remove float bowl, jets, needle valve
3. Cleaning: Use carburetor cleaner, compressed air for passages
4. Float Level Adjustment: Set to 0.63 inches (16mm)
5. Fuel Pump: Test pressure and flow rate
6. Fuel Tank: Inspect for corrosion, clean sediment

Jet Sizes: Main jet: #130, Pilot jet: #42.5, Needle jet: 4GW1-3

Electrical System

Battery, charging system, ignition, and lighting circuits.

Testing Procedures: Battery voltage: 12.6V minimum, Charging output: 13.5-15V at 5000 RPM

Transmission & Drive

Transmission service, clutch adjustment, and final drive maintenance.

1. Transmission Oil Change: Drain and refill with 10W-30, capacity 1.6 quarts
2. Clutch Adjustment: Adjust cable free play to 0.2-0.3 inches
3. Shift Mechanism: Inspect shift forks, drum, and gears
4. Final Drive: Drain and refill with 80W-90 gear oil
5. Drive Shaft: Inspect U-joints and splines

WARNING! Transmission must be cool before draining oil. Use proper gear oil specifications.

Chassis & Suspension

Frame inspection, suspension service, and steering components.

1. Frame Inspection: Check for cracks, bends, or damage
2. Front Suspension: Inspect A-arms, bushings, shock absorbers
3. Rear Suspension: Check swingarm bearings, shock linkage
4. Steering: Inspect stem bearings, adjust preload
5. Wheels & Tires: Check for damage, proper inflation

Torque Specifications: Axle nuts: 65 ft-lb, Lug nuts: 25 ft-lb, Shock mounting bolts: 35 ft-lb

Brake System

Hydraulic disc brake service and maintenance procedures.

1. Brake Fluid Change: Use DOT 4 brake fluid, bleed system
2. Brake Pad Replacement: Inspect pads for wear, replace if below 1mm
3. Brake Disc Inspection: Check for warping, minimum thickness 3.0mm
4. Caliper Service: Clean and lubricate sliding pins
5. Master Cylinder: Inspect for leaks, rebuild if necessary

CAUTION! Brake fluid is corrosive. Avoid contact with painted surfaces.

Troubleshooting

Compression Test: Minimum 120 psi, maximum variation 14 psi between cylinders

Wiring Diagrams

Complete electrical schematics for the 1987 Yamaha Warrior ATV.

• Main Harness: Color-coded wiring diagram with connector locations
• Ignition System: CDI unit, pickup coil, ignition coil circuits
• Charging System: Stator, regulator/rectifier, battery connections
• Lighting System: Headlight, taillight, brake light circuits
• Starting System: Starter motor, solenoid, safety switches

Note: All wire colors and connector positions shown in detailed diagrams. Use multimeter for circuit testing.