1987 TRX250R Service Manual

The 1987 Honda TRX250R is a high-performance all-terrain vehicle featuring a liquid-cooled 246cc two-stroke engine, Pro-Link rear suspension, and sport-oriented design. This service manual covers maintenance procedures, specifications, troubleshooting, and repair instructions for engine, transmission, chassis, electrical systems, and suspension components. Below are key sections for technical data, maintenance schedules, troubleshooting, and repair procedures.

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

General Information

Key components: Liquid-cooled 246cc two-stroke engine, Mikuni VM34SS carburetor, CDI ignition, Pro-Link rear suspension, front and rear hydraulic disc brakes.

Component	Description
Engine Type	246cc liquid-cooled two-stroke single
Bore x Stroke	66.4mm x 72.0mm
Compression Ratio	8.4:1
Carburetor	Mikuni VM34SS
Ignition System	CDI (Capacitor Discharge Ignition)
Starting System	Kick starter
Transmission	5-speed manual with reverse
Final Drive	Chain drive
Suspension Front	Independent double wishbone
Suspension Rear	Pro-Link swingarm

Specifications

Overall Length: 1,755 mm (69.1 in)
Overall Width: 1,065 mm (41.9 in)
Overall Height: 1,035 mm (40.7 in)
Wheelbase: 1,210 mm (47.6 in)
Ground Clearance: 145 mm (5.7 in)
Dry Weight: 159 kg (350 lbs)
Fuel Capacity: 9.5 liters (2.5 US gal)
Oil Capacity: 1.2 liters (1.3 US qt)
Tire Size Front: 22 x 7-10
Tire Size Rear: 20 x 10-9

Periodic Maintenance

Regular maintenance schedule for optimal performance and longevity.

Engine Oil: Change every 6 months or 500 miles
Air Filter: Clean every 3 months or 250 miles
Spark Plug: Replace every 12 months or 1,000 miles
Brake Fluid: Replace every 2 years
Chain Adjustment: Check every 100 miles
Wheel Bearings: Lubricate every 500 miles
Suspension: Check for leaks monthly

WARNING! Always use genuine Honda parts and recommended lubricants. Wear protective equipment during maintenance.

Engine Service

Two-stroke engine maintenance and repair procedures.

Cylinder Head: Torque to 20 ft-lb in crisscross pattern
Piston Installation: Ring end gaps staggered 120° apart
Reed Valve: Inspect for cracks or damage during service
Cooling System: Check radiator cap pressure (0.9-1.1 kg/cm²)
Exhaust System: Clean power valve every 100 hours
Ignition Timing: Set to 1.8mm BTDC at 2,000 RPM

CAUTION! Engine must be cool before disassembly. Use proper torque specifications.

Fuel System

Mikuni VM34SS carburetor service and fuel system maintenance.

Carburetor Float Level: 16.5mm ± 1.0mm
Main Jet: #158 standard
Pilot Jet: #58 standard
Needle Jet: 4DP1-3
Air Screw: 1.5 turns out from seated position
Fuel Mix Ratio: 20:1 (break-in), 32:1 (normal operation)

Tip: Use fresh premium unleaded gasoline with recommended two-stroke oil.

Electrical System

CDI ignition, lighting, and electrical component service.

Component	Specification
Spark Plug	NGK BR8ES (gap 0.6-0.7mm)
Ignition Coil Resistance	Primary: 0.1-0.3Ω, Secondary: 4.7-7.3kΩ
Battery	12V 4Ah
Stator Output	14V AC at 5,000 RPM
Headlight	12V 30/30W

Chassis & Suspension

Frame, suspension, and steering component service.

Front Suspension: Oil capacity 330cc per fork, oil weight 10W
Rear Shock: Nitrogen pressure 142-156 psi
Steering Stem: Torque steering stem nut to 65 ft-lb
Wheel Alignment: Toe-in 0-10mm
Frame Inspection: Check for cracks at stress points

WARNING! Always support vehicle securely with stands before working on suspension.

Transmission & Drive

5-speed transmission and final drive maintenance.

Transmission Oil: Capacity 1.2L, change every 1,000 miles
Clutch: Cable free play 10-20mm at lever
Shift Mechanism: Check detent spring tension
Chain: Adjust to 40-50mm free play
Sprockets: Replace if teeth are hooked or worn

Brake System

Front and rear hydraulic disc brake service.

Component	Specification
Brake Fluid	DOT 4
Disc Thickness	Front: 4.0mm min, Rear: 4.0mm min
Pad Thickness	1.5mm minimum
Master Cylinder	Front: 11mm, Rear: 12.7mm

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

Troubleshooting

Symptom	Possible Cause	Corrective Action
Hard starting	Fouled spark plug, stale fuel	Replace spark plug; drain old fuel; check compression
Poor performance	Clogged carburetor, worn piston	Clean carburetor; inspect piston and cylinder
Transmission noise	Low oil level, worn gears	Check oil level; inspect transmission components
Overheating	Low coolant, clogged radiator	Check coolant level; clean radiator fins
Electrical failure	Bad connections, failed stator	Check wiring connections; test stator output

Service Note: Always refer to torque specifications in manual. Use proper safety equipment.

Parts Support: Contact authorized Honda dealer for genuine parts.