1986 Honda CR500 Service Manual

The 1986 Honda CR500 is a legendary two-stroke motocross bike featuring a 491cc liquid-cooled engine, 5-speed transmission, front and rear disc brakes, and advanced suspension for its time. This service manual covers maintenance procedures, specifications, troubleshooting, and repair instructions for the complete motorcycle system. Below are key sections for safety, specifications, maintenance procedures, troubleshooting, and technical data.

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

General Information

Key components: 491cc two-stroke engine, Mikuni carburetor, CDI ignition, aluminum frame, Showa suspension, hydraulic disc brakes.

Component	Description
Engine Type	Single cylinder, two-stroke, liquid-cooled
Displacement	491cc
Bore x Stroke	89.0 x 79.0 mm
Compression Ratio	7.8:1
Carburetor	Mikuni VM38SS
Ignition	CDI (Capacitor Discharge Ignition)
Transmission	5-speed constant mesh
Final Drive	Chain
Frame	Aluminum semi-double cradle
Suspension	Showa front forks, Pro-Link rear

Specifications

Engine: 491cc liquid-cooled two-stroke single cylinder
Power Output: 60 hp @ 6500 rpm
Torque: 48 Nm @ 6000 rpm
Fuel System: Mikuni VM38SS carburetor
Ignition: CDI electronic ignition
Transmission: 5-speed, wet multi-plate clutch
Front Suspension: 43mm Showa telescopic fork, 300mm travel
Rear Suspension: Pro-Link system, 320mm travel
Front Brake: Single disc, 240mm
Rear Brake: Single disc, 220mm
Fuel Capacity: 9.5 liters
Dry Weight: 108 kg

Periodic Maintenance

Regular maintenance schedule for optimal performance and longevity.

Engine oil change: Every 15 hours or 500 miles
Air filter cleaning: Every 10 hours or after dusty conditions
Spark plug replacement: Every 25 hours
Coolant replacement: Every 50 hours or annually
Chain adjustment: Every 5 hours or as needed
Brake fluid change: Every 100 hours or annually
Fork oil change: Every 100 hours or annually

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

Engine Service

Complete engine disassembly, inspection, and reassembly procedures.

Top end rebuild: Piston and ring replacement procedure
Crankshaft service: Inspection and replacement guidelines
Cylinder inspection: Measuring wear and honing procedures
Power valve service: Cleaning and adjustment
Cooling system: Radiator service and water pump repair
Clutch service: Plate replacement and adjustment

CAUTION! Use proper torque specifications and follow assembly sequence precisely.

Fuel System

Mikuni VM38SS carburetor service and fuel system maintenance.

Carburetor disassembly: Step-by-step teardown
Jet cleaning: Main jet, pilot jet, and needle procedures
Float level adjustment: Setting to factory specifications
Air screw adjustment: Fine-tuning for optimal performance
Fuel petcock service: Inspection and repair
Fuel line replacement: Proper routing and securing

Tip: Always clean carburetor in well-ventilated area and use compressed air for passages.

Electrical System

CDI ignition, lighting, and charging system service.

CDI unit testing: Resistance and voltage specifications
Stator service: Inspection and replacement procedure
Spark plug selection: Proper heat range and gap settings
Wiring harness: Inspection and repair procedures
Kill switch testing: Continuity and function verification
Battery service: Maintenance and charging procedures

WARNING! Disconnect battery before electrical work to prevent shorts.

Chassis & Suspension

Frame, suspension, and steering maintenance procedures.

Front fork service: Oil change and seal replacement
Rear shock service: Nitrogen charging and seal replacement
Steering head bearing: Adjustment and replacement
Swingarm bearing: Inspection and lubrication
Wheel bearing service: Inspection and replacement
Frame inspection: Crack detection and repair

CAUTION! Use proper suspension tools and follow safety procedures.

Brake System

Hydraulic disc brake service and maintenance.

Brake pad replacement: Front and rear procedures
Brake disc inspection: Measuring thickness and runout
Brake fluid bleeding: Complete system procedure
Caliper service: Piston and seal replacement
Master cylinder service: Rebuild and adjustment
Brake line inspection: Checking for wear and damage

WARNING! Use only DOT 4 brake fluid and avoid contamination.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Hard starting	Fouled plug, compression loss	Replace spark plug; check compression; clean carburetor
Poor performance	Clogged jets, air leak	Clean carburetor; check reed valves; inspect base gasket
Overheating	Low coolant, water pump	Check coolant level; inspect water pump; clean radiator
Transmission issues	Worn gears, shift mechanism	Inspect shift forks; check gear engagement; replace worn parts
Brake fade	Contaminated fluid, worn pads	Bleed brakes; replace pads; clean rotors

Diagnostic: Use factory service manual procedures for systematic troubleshooting.

Wiring Diagrams

Complete electrical schematics for all systems.

CDI ignition system wiring diagram
Lighting circuit schematic
Charging system wiring
Kill switch and starter circuits
Ground point locations and connections

Note: Refer to color codes and connector locations for proper diagnosis.

Torque Specifications

Component	Torque Value	Notes
Cylinder head nuts	30 Nm	Criss-cross pattern
Spark plug	25 Nm	With copper washer
Clutch spring bolts	10 Nm	Even tightening
Front axle nut	80 Nm	With cotter pin
Rear axle nut	110 Nm	With cotter pin
Sprocket bolts	25 Nm	Use thread locker
Fork clamp bolts	25 Nm	Upper and lower
Shock mounting bolts	55 Nm	Front and rear

Service: For technical support contact Honda Customer Service or authorized dealer.