1987 KX125 Service Manual

The 1987 KX125 is a high-performance motocross motorcycle featuring a liquid-cooled 125cc two-stroke engine, 6-speed transmission, Uni-Trak rear suspension system, front disc brake, and lightweight aluminum frame. This service manual covers maintenance procedures, specifications, troubleshooting, and repair instructions for proper servicing and optimal performance.

General Information

This manual provides detailed service information for the 1987 Kawasaki KX125 motocross motorcycle. Includes safety precautions, tool requirements, and general maintenance procedures.

Specifications

• Engine Type: Liquid-cooled, single-cylinder two-stroke
• Displacement: 124cc
• Bore x Stroke: 56.0 x 50.6mm
• Compression Ratio: 8.4:1
• Carburetor: Mikuni VM32SS
• Transmission: 6-speed constant mesh
• Final Drive: Chain 520-112 links
• Suspension Front: Telescopic fork, 275mm travel
• Suspension Rear: Uni-Trak swingarm, 310mm travel
• Brakes Front: Single disc, 240mm
• Brakes Rear: Single drum, 180mm
• Fuel Capacity: 8.5 liters

Periodic Maintenance

Regular maintenance schedule for optimal performance and longevity.

1. Before Each Ride: Check fuel level, tire pressure, chain tension, controls operation
2. Every 10 Hours: Clean air filter, check spark plug, inspect brakes
3. Every 20 Hours: Change transmission oil, check wheel bearings
4. Every 50 Hours: Replace spark plug, clean carburetor, check suspension
5. Every 100 Hours: Top end rebuild, inspect crankshaft, replace piston rings

WARNING! Always use proper safety equipment and follow torque specifications.

Engine

Complete engine service procedures including disassembly, inspection, and reassembly.

1. Cylinder Head: Removal, decarbonizing, gasket replacement
2. Cylinder: Inspection, honing procedures, measurement
3. Piston: Removal, ring installation, clearance checking
4. Crankshaft: Inspection, connecting rod play measurement
5. Ignition System: Timing adjustment, CDI unit testing
6. Exhaust System: Power valve cleaning and adjustment

Torque Specifications: Cylinder head bolts 22 Nm, spark plug 25 Nm

Cooling System

Liquid cooling system maintenance and repair procedures.

1. Check coolant level in radiator when cold
2. Bleed air from system after service
3. Test radiator cap pressure (0.9-1.1 kg/cm²)
4. Inspect water pump impeller and seals
5. Flush system annually with distilled water

Coolant Capacity: 950ml. Use ethylene glycol antifreeze mixed 50/50 with distilled water.

Fuel System

Carburetor service and fuel system maintenance.

Fuel Mix: Premium unleaded gasoline with 2-stroke oil at 32:1 ratio for competition use.

Electrical System

Complete electrical system testing and service procedures.

1. Ignition Coil: Primary resistance 0.1-0.2Ω, Secondary 4.7-7.2kΩ
2. Spark Plug: NGK BR9ES, gap 0.6-0.7mm
3. CDI Unit: Resistance testing procedures
4. Lighting Coil: Output testing and replacement
5. Battery: Maintenance-free type, voltage checking

Chassis

Frame, suspension, and brake system service.

1. Front Fork: Oil change procedure, seal replacement
2. Rear Suspension: Uni-Trak linkage service and lubrication
3. Steering Head: Bearing adjustment and replacement
4. Wheels: Spoke tension, rim runout measurement
5. Brakes: Pad replacement, disc measurement, drum adjustment

Fork Oil: 10W fork oil, 435ml per leg

Transmission

6-speed transmission service and clutch maintenance.

1. Clutch: Plate inspection, cable adjustment, basket service
2. Gearshift Mechanism: Drum and fork inspection
3. Transmission Oil: SAE 10W-40, 750ml capacity
4. Shift Pattern: 1-down, 5-up
5. Primary Drive: Gear inspection and replacement

Clutch Cable Free Play: 10-15mm at lever

Troubleshooting

Compression Test: Should be 120-150 psi for proper engine condition.

Service: Contact authorized Kawasaki dealer for technical support and genuine parts.