Segment:
Competitive motocross market, known for its agility and potent two-stroke engine.
Competitors:
Honda CR125R, KTM 125 SX, Suzuki RM125, Kawasaki KX125.
Engine Type:
Liquid-cooled, 2-stroke, reed valve inducted, single-cylinder.
Chassis Design:
Lightweight aluminum frame for enhanced handling and agility.
Suspension Performance:
Industry-leading KYB (Kayaba) suspension components known for their adjustability and plush feel.
Engine Mechanical:
Detailed disassembly, assembly, inspection, and repair of the entire engine, including cylinder, piston, crankshaft, connecting rod, bearings, seals, and gaskets.
Cooling System:
Radiator, hoses, thermostat (if applicable), water pump, and coolant specifications.
Fuel System:
Carburetor (Mikuni VM34 or similar), fuel pump (if applicable), fuel lines, fuel tank, and fuel filter.
Ignition System:
CDI unit, ignition coil, spark plug, stator, and timing specifications.
Transmission And Drivetrain:
Gearbox disassembly, inspection, and repair; clutch assembly, operation, and adjustment; chain and sprocket maintenance; drive system.
Suspension Front:
Fork (KYB or similar) disassembly, seal replacement, oil level and type, damping adjustments, and spring replacement.
Suspension Rear:
Monoshock (Kayaba or similar) disassembly, shock absorber service, linkage maintenance, and spring preload adjustments.
Brakes Front:
Hydraulic disc brake system, caliper overhaul, master cylinder service, pad replacement, fluid specifications, and bleeding procedures.
Brakes Rear:
Hydraulic disc brake system, caliper overhaul, master cylinder service, pad replacement, fluid specifications, and bleeding procedures.
Electrical System:
Wiring diagrams, lighting, battery maintenance, fuses, switches, and troubleshooting for electrical faults.
Chassis And Bodywork:
Frame inspection, subframe, footpegs, seat, fuel tank removal and installation, body panel removal and installation, handlebars, and controls.
Wheels And Tires:
Spoke tensioning, rim maintenance, bearing replacement, tire selection and installation, and balancing.
Routine Maintenance:
Oil changes, filter replacements, chain lubrication and adjustment, air filter cleaning, spark plug inspection and replacement.
Engine Rebuild:
Comprehensive step-by-step instructions for complete engine overhaul, including torque specifications and clearances.
Suspension Tuning:
Guidance on adjusting damping, compression, rebound, and sag for optimal performance.
Carburetor Tuning:
Jetting recommendations, idle speed adjustment, and general tuning for various conditions.
Troubleshooting Guide:
Systematic approach to diagnosing and resolving common performance issues and failures.
Wiring Diagrams:
Detailed electrical schematics for easy fault finding and component identification.
Depth:
Comprehensive, covering everything from basic owner maintenance to complete engine and suspension rebuilds, intended for both home mechanics and professional technicians.
Type:
Liquid-cooled, 2-stroke, reed valve induction, single-cylinder
Bore X Stroke:
54.0 mm x 54.5 mm
Compression Ratio:
8.8:1 (typical, check manual for exact spec)
Carburetor:
Mikuni VM34SS (or similar)
Ignition:
CDI (Capacitor Discharge Ignition)
Horsepower Estimated:
35-40 HP (at peak, estimated based on model year)
Torque Estimated:
Approximately 18-20 lb-ft (at peak, estimated)
Fuel Type:
Unleaded gasoline with 2-stroke oil pre-mix (typically 20:1 or 32:1, consult manual for precise ratio)
Fuel Tank Capacity:
7.0 Liters (1.85 US gallons)
Oil Change:
Every 10-15 hours of riding or as specified by the manual.
Air Filter Cleaning:
After every few rides, or more frequently in dusty conditions.
Chain Lubrication:
Every 2-3 rides or after washing/rain.
Spark Plug Inspection:
Every 10-15 hours of riding.
Top End Rebuild:
Typically every 50-100 hours of riding, depending on usage and maintenance.
Engine Oil Type:
Specific 2-stroke oil pre-mix ratio (e.g., Yamalube 2R or equivalent, typically 20:1 or 32:1 – *Consult manual for exact specification*).
Transmission Oil Type:
Yamalube 10W-40 or equivalent API GL-4 gear oil (capacity typically 0.8-1.0 Liters).
Coolant Type:
Permanent type antifreeze coolant (ethylene glycol based), typically a 50/50 mix with distilled water.
Brake Fluid Type:
DOT 4 hydraulic brake fluid.
Clutch Wear:
Clutch plates can wear over time, especially with aggressive riding; regular inspection and replacement as needed.
Suspension Seals:
Fork and shock seals are wear items and can leak; replacement is a common maintenance task.
Power Valve System:
The automatic power valve system requires periodic cleaning and inspection to ensure proper operation and performance.
Carburetor Tuning:
Requires proper jetting and adjustment for optimal performance across different altitudes and temperatures.
