Vehicle Class:
Competition Motocross Motorcycles
Target User:
Enthusiasts and professional racers focused on performance and reliability in off-road competition.
Competitors Era:
Honda CR Series, Yamaha YZ Series, Suzuki RM Series, KTM SX Series.
Vehicle Design:
Two-stroke engines, powerful for their displacement, focusing on lightweight design and aggressive power delivery for motocross racing.
Manual Value Proposition:
Provides the essential, in-depth knowledge required to maintain and repair these high-performance machines to factory standards, crucial for competitive edge.
Engine Internal:
Engine disassembly, inspection, repair, and reassembly for both KX125 and KX250 models, including top-end, bottom-end, lubrication system, and cooling system.
Fuel System:
Carburetor tuning, maintenance, and overhaul; fuel tank and petcock inspection and repair.
Ignition System:
CDI unit testing, stator and coil inspection, spark plug specifications, and troubleshooting.
Transmission Drivetrain:
Gearbox inspection, repair, clutch service (friction plates, steel plates, springs), and chain/sprocket maintenance.
Suspension Front:
Front fork disassembly, seal replacement, oil level and type specifications, damping adjustments, and spring rates for both KX125 and KX250.
Suspension Rear:
Monoshock rear suspension service, linkage inspection and lubrication, shock absorber overhaul, nitrogen charging, and spring adjustment.
Brakes Front:
Hydraulic front brake system service, caliper inspection, pad replacement, master cylinder overhaul, and fluid specifications.
Brakes Rear:
Rear brake drum or disc service, shoe/pad replacement, and linkage adjustment.
Cooling System:
Radiator inspection, coolant type and capacity, water pump seal replacement, and thermostat operation.
Electrical System:
Wiring diagrams, lighting system troubleshooting, battery maintenance, and kill switch functionality.
Chassis Frame:
Frame inspection, steering head bearing service, and general chassis component maintenance.
Bodywork Plastics:
Removal and installation of fenders, side panels, seat, and fuel tank.
Preventative Maintenance:
Detailed service intervals for oil changes, filter replacements, chain lubrication, spark plug checks, and brake inspections.
Troubleshooting:
Systematic diagnostic procedures for common starting issues, performance problems, and component failures.
Engine Rebuild:
Complete engine disassembly, cleaning, measurement of critical components (piston, cylinder bore, connecting rod), and rebuild procedures with torque specifications.
Carburetor Rebuild:
Step-by-step instructions for disassembling, cleaning, replacing jets and needles, and reassembling the carburetor.
Suspension Servicing:
Detailed procedures for fork oil changes, seal replacement, and rear shock absorber maintenance.
Clutch Adjustment Replacement:
Procedures for adjusting clutch cable play and replacing clutch plates.
Wheel Bearing Replacement:
Instructions for replacing wheel bearings and hub maintenance.
Brake Bleeding:
Proper procedures for bleeding hydraulic brake systems.
Depth:
Extremely high. Covers all aspects from routine maintenance to complete engine and chassis rebuilds, including detailed torque specifications, clearances, and tolerances.
Diagnostic Capabilities:
Advanced diagnostic procedures for identifying and resolving mechanical and electrical issues.
Data Availability:
Includes critical measurements, specifications, and tolerances required for precision repairs.
Kx125 Engine Type:
Liquid-cooled, 2-stroke, reed valve induction
Kx125 Displacement:
124 cc (approximate, varies slightly by year)
Kx125 Bore X Stroke:
Typically 54.0 x 54.5 mm (check specific year)
Kx250 Engine Type:
Liquid-cooled, 2-stroke, reed valve induction
Kx250 Displacement:
249 cc (approximate, varies slightly by year)
Kx250 Bore X Stroke:
Typically 66.4 x 72.0 mm (check specific year)
Kx125 Horsepower:
Approximately 35-40 HP (crank horsepower, varies by year)
Kx250 Horsepower:
Approximately 45-50 HP (crank horsepower, varies by year)
Carburetor Kx125:
Keihin PWK (e.g., 35mm, 36mm, 38mm, varies by year)
Carburetor Kx250:
Keihin PWK (e.g., 38mm, 39mm, 40mm, varies by year)
Fuel Type:
Unleaded gasoline (minimum 91 octane recommended), mixed with 2-stroke oil.
2 Stroke Oil Mix Ratio:
Typically 20:1 or 32:1 (refer to specific manual for exact ratio and oil type).
Transmission Type:
6-speed constant mesh, sequential manual
Optional Transmission:
N/A (all models are manual 6-speed)
Clutch Type:
Wet, multi-disc, manual operation
Gear Ratios:
Specific gear ratios are detailed in the manual for each model and year.
Final Drive:
O-ring sealed chain, 520 pitch (typical), sprocket ratios vary.
Transmission Oil Type:
Kawasaki Genuine Gear Oil (or equivalent 80W/90 API GL-4 specification).
Transmission Oil Capacity:
Approx. 0.7 - 1.0 Liters (refer to manual for exact specification).
Wheelbase Kx125:
Approx. 1430-1445 mm (56.3-56.9 in), varies by year
Wheelbase Kx250:
Approx. 1470-1485 mm (57.9-58.5 in), varies by year
Seat Height Kx125:
Approx. 960 mm (37.8 in), varies by year
Seat Height Kx250:
Approx. 970 mm (38.2 in), varies by year
Dry Weight Kx125:
Approx. 87-90 kg (192-198 lbs), varies by year
Dry Weight Kx250:
Approx. 97-100 kg (214-220 lbs), varies by year
Fuel Capacity:
Approx. 8.0 Liters (2.1 US gal), varies by year
Engine Oil Change:
Every 10-15 hours of riding or annually, whichever comes first (refer to manual for specifics).
Air Filter Cleaning:
After every few rides, or more frequently in dusty conditions.
Spark Plug Check:
Every 10-20 hours of riding.
Chain Lubrication Adjustment:
Every ride or every few hours, depending on conditions.
Suspension Service:
Fork seal replacement as needed; full fork/shock service every 20-40 hours of riding.
Coolant:
High-quality ethylene glycol based coolant with de-ionized water (50/50 mix recommended).
Brake Fluid:
DOT 4 hydraulic brake fluid.
Fork Oil:
Specific suspension fluid (e.g., Showa SS-03, KYB Fork Oil) with specified viscosity and level (e.g., 0.5L, 5W).
Power Valve Sticking:
Carbon buildup can cause the power valve mechanism to stick, affecting performance. Requires regular cleaning.
Clutch Wear:
Aggressive riding can lead to premature wear of clutch plates.
Suspension Seals:
Fork and shock seals can degrade over time, leading to leaks. Regular maintenance is crucial.
Carburetor Jetting:
Requires careful jetting based on altitude, temperature, and modifications for optimal performance.
