Segment:
High-performance Motocross / Off-road Competition
Target Audience:
Motocross racers, off-road enthusiasts, and mechanics seeking to maintain and repair their Kawasaki KX125 and KX250 motorcycles.
Competitors:
Honda CR125R/CR250R, Yamaha YZ125/YZ250, Suzuki RM125/RM250, KTM 125 EXC/200 EXC/250 EXC.
Vehicle Focus:
Renowned for powerful two-stroke engines, agile handling, and race-winning pedigree in the highly competitive motocross arena.
Manual Value Proposition:
Provides essential technical data, step-by-step repair instructions, and troubleshooting guides to keep these performance-oriented machines in peak condition.
Engine System:
Complete engine overhaul, top-end and bottom-end rebuilds, carburetor tuning and rebuilding, ignition system diagnosis and repair, cooling system maintenance.
Chassis System:
Frame inspection and repair, suspension (front forks and rear shock) maintenance and overhaul, steering system, wheels, hubs, and spokes. Brake system (front and rear hydraulic discs) service and bleeding. Clutch system operation and maintenance.
Electrical System:
Wiring diagrams, lighting systems, ignition control, troubleshooting electrical faults.
Fuel And Ignition:
Detailed carburetor disassembly, cleaning, inspection, and jetting procedures. Ignition system testing, including CDI unit and stator checks.
Exhaust System:
Power valve operation, cleaning, and adjustment procedures for optimal performance and engine response.
Lubrication System:
Details on the automatic oil injection system (if equipped on specific models) or proper premix ratios.
Routine Maintenance:
Oil changes, air filter cleaning/replacement, chain adjustment and lubrication, spark plug replacement, coolant checks.
Repair Procedures:
Engine disassembly and reassembly, transmission service, clutch replacement, brake caliper rebuilding, suspension component replacement, carburetor jetting and cleaning.
Troubleshooting:
Diagnosis of common starting issues, engine performance problems, electrical faults, and suspension noise.
Engine Rebuild:
Complete step-by-step guides for piston and ring replacement, cylinder inspection and re-boring, crankshaft and bearing replacement, and crankcase assembly.
Suspension Overhaul:
Front fork seal replacement, fork oil change and level adjustment, rear shock absorber service and re-gassing procedures.
Diagnostic Charts:
Flowcharts and tables for diagnosing common engine, electrical, and chassis issues.
Depth:
Comprehensive, covering everything from basic maintenance to full engine rebuilds and advanced troubleshooting. Includes detailed torque specifications, clearances, and diagnostic procedures.
Diagnostic Tools:
While not requiring specialized electronic diagnostic tools, the manual details how to use basic tools like a multimeter for electrical testing.
PDF Quality:
High-resolution, searchable PDF with clear diagrams and text.
Searchability:
Fully searchable PDF text for quick access to specific information.
Printability:
Printable pages for workshop use.
Diagram Clarity:
High-resolution images and diagrams that are clear and easy to follow for repair processes.
Kx125 Engine Type:
Liquid-cooled, 2-stroke, single-cylinder
Kx125 Displacement:
124 cc
Kx125 Bore X Stroke:
54.0 x 54.5 mm
Kx250 Engine Type:
Liquid-cooled, 2-stroke, single-cylinder
Kx250 Displacement:
249 cc
Kx250 Bore X Stroke:
66.4 x 72.0 mm
Kx125 Compression Ratio:
Varies by year, typically around 8.7:1 to 9.2:1
Kx250 Compression Ratio:
Varies by year, typically around 7.9:1 to 8.2:1
Kx125 Horsepower:
Approx. 38-40 HP (estimated, varies by year and tune)
Kx250 Horsepower:
Approx. 45-48 HP (estimated, varies by year and tune)
Kx125 Torque:
Approx. 20-22 lb-ft (estimated, varies by year and tune)
Kx250 Torque:
Approx. 25-28 lb-ft (estimated, varies by year and tune)
Carburetor:
Mikuni VM28SS (KX125), Keihin PWK39 (KX250) - specific models vary by year.
Fuel Type:
Unleaded gasoline, minimum 91 octane recommended (premium)
Premix Ratio:
50:1 with high-quality 2-stroke premix oil (e.g., Bel-Ray, Motul, Yamalube)
Wheelbase:
KX125: ~1475 mm (58.1 in); KX250: ~1485 mm (58.5 in) (approximate, varies by year)
Ground Clearance:
Approx. 330-340 mm (13.0-13.4 in) (varies by year)
Seat Height:
Approx. 960-970 mm (37.8-38.2 in) (varies by year)
Dry Weight:
KX125: ~92 kg (203 lbs); KX250: ~100 kg (220 lbs) (approximate, varies by year)
Fuel Capacity:
Approx. 8.0 Liters (2.1 US gallons)
Curb Weight:
N/A (typically listed as dry weight for these models)
Oil Change Frequency:
Every 15-20 hours of operation or as specified for the gearbox oil. Engine oil is mixed with fuel for two-stroke lubrication.
Air Filter Cleaning:
After every ride or more frequently in dusty conditions.
Chain Maintenance:
Check and lubricate before every ride, adjust chain slack every 5-10 hours.
Gearbox Oil Type:
SAE 10W-30 API SG or higher motorcycle gear oil (e.g., Kawasaki Genuine Oil, Motul Gear 300).
Coolant Type:
Permanent type anti-freeze coolant (50% solution with distilled water).
Brake Fluid Type:
DOT 4 hydraulic brake fluid
Kx125 Common Problems:
Carburetor jetting sensitivity to altitude and temperature, occasional clutch basket wear, exhaust power valve adjustment.
Kx250 Common Problems:
Power valve operation can be sensitive, occasional crank seal leaks, kickstarter engagement issues if not properly maintained.
Engine Mounts:
Specific torque values for cylinder head, cylinder base, and engine mounts are detailed in the manual.
Wheel Axles:
Specified torque for front and rear wheel axles to ensure proper bearing preload and security.
Spark Plug Torque:
Specified torque for proper sealing without damaging threads.
Carburetor Mounting Torque:
Torque for mounting the carburetor to the intake manifold.
Kawasaki Legacy:
Kawasaki has a long and successful history in motocross racing, with the KX series being a dominant force for decades.
Kx Series Development:
The KX125 and KX250 were continuously developed for performance, handling, and reliability to meet the demands of professional motocross and supercross.
Kx Design Philosophy:
Focus on lightweight construction, strong two-stroke powerbands, and refined suspension for competitive motocross performance.
Manufacturing Period:
These models represent a specific generation of Kawasaki's 125cc and 250cc two-stroke motocross bikes, popular in the early to mid-2000s.
