1988 KX250 Service Manual

The 1988 KX250 is a high-performance motocross motorcycle featuring a liquid-cooled 249cc two-stroke engine, 43mm conventional front forks, Uni-Trak rear suspension system, and advanced chassis design for competitive racing. This service manual covers maintenance procedures, specifications, troubleshooting, and repair instructions for optimal performance and longevity.

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

General Information

This manual provides detailed service information for the 1988 Kawasaki KX250 motocross motorcycle. Includes safety precautions, tool requirements, and general maintenance procedures.

Component	Description
Model	KX250-A1 (1988)
Engine Type	Liquid-cooled, single cylinder, two-stroke
Displacement	249cc
Bore x Stroke	67.0 x 70.8mm
Compression Ratio	8.4:1
Lubrication System	Premix (oil in fuel)
Ignition System	CDI (Capacitor Discharge Ignition)
Starting System	Kick starter
Transmission	5-speed constant mesh
Final Drive	Chain

Specifications

Overall Length: 2,185mm
Overall Width: 830mm
Overall Height: 1,260mm
Wheelbase: 1,485mm
Ground Clearance: 345mm
Seat Height: 955mm
Dry Weight: 102kg
Fuel Capacity: 9.5 liters
Front Suspension: 43mm telescopic fork, 300mm travel
Rear Suspension: Uni-Trak system, 320mm travel
Front Brake: Single disc, 240mm
Rear Brake: Single disc, 240mm

Periodic Maintenance

Regular maintenance schedule for optimal performance and safety.

Before each ride: Check fuel level, tire pressure, chain tension, brake operation.
Every 15 hours: Clean air filter, check spark plug, inspect brakes.
Every 30 hours: Change transmission oil, check wheel bearings.
Every 60 hours: Replace spark plug, inspect piston and rings.
Every 100 hours: Top end rebuild recommended for competition use.

WARNING! Always use proper safety equipment and follow torque specifications. Use only Kawasaki genuine parts for replacement.

Engine Service

Detailed procedures for engine disassembly, inspection, and reassembly.

Service Item	Specification
Spark Plug	BR8ES (NGK)
Spark Plug Gap	0.6-0.7mm
Fuel/Oil Ratio	32:1 (premium unleaded)
Idle Speed	1,300 ± 100 rpm
Compression Pressure	120-150 psi
Piston Clearance	0.045-0.055mm
Piston Ring End Gap	0.40-0.60mm

CAUTION! Engine must be completely cool before disassembly. Mark all components for proper reassembly.

Fuel System

Carburetor specifications and maintenance procedures.

Carburetor Type: Keihin PWK38
Main Jet: #168
Pilot Jet: #48
Needle Jet: R1470N
Needle Position: 3rd clip from top
Float Height: 16mm
Air Screw: 1.5 turns out

Tip: Clean carburetor thoroughly after extended storage. Use compressed air to clear jets.

Chassis & Suspension

Frame, suspension, and steering maintenance procedures.

Front Fork Oil: 10W, 486ml per leg
Fork Spring Free Length: 525mm
Rear Shock Oil: 5W, 190ml
Steering Head Bearing Torque: 40-50 Nm
Axle Nut Torque: Front: 65 Nm, Rear: 110 Nm
Swingarm Pivot Torque: 95 Nm
Chain Tension: 35-45mm free play

Electrical System

Ignition, lighting, and charging system specifications.

Component	Specification
Ignition Timing	1.8mm BTDC
Spark Advance	Mechanical advance
Stator Resistance	Primary: 0.1-0.2Ω
Pickup Coil Resistance	110-190Ω
Battery	Not applicable (magneto only)
Bulbs	Headlight: N/A, Brake light: N/A

Transmission

Gearbox and clutch service procedures.

Transmission Oil: SAE 10W-40, 850ml
Oil Change Interval: Every 15 race hours
Clutch Type: Wet multi-plate
Clutch Spring Free Length: 46.8mm
Clutch Plate Thickness: Friction: 2.9-3.1mm, Steel: 1.5-1.6mm
Gear Ratios: 1st: 2.083, 2nd: 1.688, 3rd: 1.389, 4th: 1.174, 5th: 1.043

Brake System

Front and rear disc brake maintenance.

Front Brake Disc Thickness: 4.0mm (min: 3.5mm)
Rear Brake Disc Thickness: 4.0mm (min: 3.5mm)
Brake Pad Thickness: 5.0mm (min: 1.0mm)
Brake Fluid: DOT 4
Bleed Procedure: Standard hydraulic bleeding
Master Cylinder Bore: Front: 12.7mm, Rear: 14.0mm

WARNING! Always replace brake fluid annually. Check brake system before every ride.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Hard starting	Fouled plug, compression loss	Replace spark plug; check compression; clean carburetor
Poor performance	Clogged air filter, jetting	Clean air filter; adjust carburetor jetting
Transmission noise	Worn gears, low oil	Check oil level; inspect transmission gears
Overheating	Lean mixture, coolant	Check jetting; inspect cooling system
Clutch slippage	Worn plates, weak springs	Measure clutch components; replace as needed

Service Note: Always use factory torque specifications. Keep work area clean and organized.

Technical Support: Contact Kawasaki authorized dealer for complex repairs.