1987 CR125 Manual

The 1987 Honda CR125 is a 125cc two-stroke motocross motorcycle featuring liquid cooling, a 6-speed transmission, Pro-Link rear suspension, and front disc brake. This manual covers maintenance, specifications, troubleshooting, and repair procedures for the complete motorcycle system including engine, chassis, electrical, and suspension components.

1. Specifications 2. Maintenance Schedule 3. Engine Service 4. Chassis & Suspension 5. Electrical System 6. Carburetor Adjustment 7. Troubleshooting 8. Torque Specifications 9. Lubrication Points 10. Safety Information 11. Warranty & Support

Specifications

Complete technical specifications for the 1987 Honda CR125 motocross motorcycle.

Component	Specification
Engine Type	124.8cc liquid-cooled single-cylinder two-stroke
Bore x Stroke	56.0mm x 50.6mm
Compression Ratio	8.2:1
Carburetor	Keihin PE28
Ignition	CDI electronic ignition
Transmission	6-speed constant mesh
Final Drive	520 chain
Suspension Front	43mm Showa conventional fork
Suspension Rear	Pro-Link single shock
Brakes Front	Single disc 240mm
Brakes Rear	Single drum 110mm
Fuel Capacity	2.3 gallons (8.7 liters)
Dry Weight	197 lbs (89 kg)

Maintenance Schedule

Regular maintenance intervals for optimal performance and longevity.

After break-in (3 hours): Check all fasteners, adjust chain, check fluid levels
Every 10 hours: Clean air filter, check spark plug, adjust carburetor
Every 20 hours: Change transmission oil, check brake pads, inspect suspension
Every 40 hours: Replace spark plug, check wheel bearings, inspect chain/sprockets
Every 100 hours: Top end rebuild, suspension service, complete inspection

WARNING! Always use genuine Honda parts for replacement. Improper maintenance can lead to component failure and injury.

Engine Service

Complete engine maintenance and repair procedures.

Top end rebuild: Remove cylinder head, replace piston and rings, inspect cylinder
Bottom end service: Split cases, replace crankshaft bearings and seals
Power valve maintenance: Clean and lubricate RC valve system
Cooling system: Flush radiator, check water pump, replace coolant
Exhaust system: Remove and clean expansion chamber, repack silencer

CAUTION! Engine components operate at high temperatures. Allow engine to cool completely before servicing.

Chassis & Suspension

Frame: Aluminum semi-double cradle with steel swingarm
Front Suspension: 43mm Showa conventional forks, 11.8 inches travel
Rear Suspension: Pro-Link system with Showa shock, 12.2 inches travel
Wheels: Front 21-inch, Rear 19-inch aluminum rims
Brakes: Front hydraulic disc, rear mechanical drum
Handlebars: Steel renthal style, 32-inch width
Footpegs: Steel serrated pegs with rubber inserts

Electrical System

Complete electrical system specifications and troubleshooting.

Components: CDI ignition, lighting coil, spark plug (NGK BR9ES), kill switch, throttle position sensor.

Battery: Not applicable - magneto powered ignition only. Lighting: Optional lighting kit available. Spark plug gap: 0.6-0.7mm. Ignition timing: Fixed at 1.5mm BTDC. Resistance values: Primary coil 0.1-0.3Ω, Secondary coil 4.5-6.5kΩ.

Carburetor Adjustment

Keihin PE28 carburetor settings and adjustment procedures.

Pilot jet: #55 standard setting
Main jet: #165 standard setting
Needle jet: 6BFY42-3, clip position 3rd from top
Air screw: 1.5 turns out from lightly seated
Float height: 16.5mm measured from bowl gasket surface

Tip: Adjust air screw for optimal idle and throttle response. Leaner for high altitude, richer for low altitude.

Playing DVD Media

This section does not apply to motorcycle manuals. Please refer to appropriate sections.

Accessibility Features

This section does not apply to motorcycle manuals. Please refer to appropriate sections.

Care & Cleaning

Proper cleaning and storage procedures for your CR125.

After riding: Wash with mild soap and water, dry thoroughly, lubricate chain, spray corrosion inhibitor on exposed metal. Storage: Drain fuel from carburetor, remove spark plug and add oil to cylinder, store in dry location, elevate tires off ground.

CAUTION! Avoid high-pressure water near bearings and seals. Do not direct water at air filter intake or electrical components.

Regulatory Information

This motorcycle is designed for closed-course competition use only. Not legal for street use in most jurisdictions. Always wear approved safety equipment including helmet, goggles, gloves, boots, and protective clothing. Honda and CR125 are registered trademarks of Honda Motor Co., Ltd.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Hard starting	Fouled plug, stale fuel	Replace spark plug, drain old fuel, clean carburetor
Poor performance	Clogged air filter, worn piston	Clean/replace air filter, inspect top end components
Transmission issues	Low oil, worn gears	Check oil level, inspect transmission components
Overheating	Low coolant, clogged radiator	Check coolant level, clean radiator fins
Brake problems	Worn pads, air in lines	Replace brake pads, bleed hydraulic system

Reset: No electronic reset required for this model.

Service: Contact authorized Honda dealer for professional service and genuine parts.