Segment:
2-stroke Motocross Motorcycle
Competitors Era:
Competed against models from Honda (CR125R), Suzuki (RM125), Kawasaki (KX125).
Engine Type:
High-performance liquid-cooled, reed-valve inducted, 2-stroke engine.
Suspension Type:
Advanced Kayaba (KYB) suspension components, including USD forks and a Monoshock rear.
Chassis Design:
Lightweight aluminum or steel frame optimized for motocross handling.
Diy Maintenance Savings:
Enables owners to save money by performing maintenance and repairs themselves, avoiding dealer labor costs.
Professional Service Replication:
Empowers users to perform repairs with the same quality and accuracy as a professional technician.
Engine Mechanical:
Complete disassembly, overhaul, and assembly of the 125cc two-stroke engine.
Fuel System:
Carburetor tuning, cleaning, rebuilding, fuel tank, fuel lines, and fuel pump (if applicable).
Ignition System:
CDI unit, spark plug, ignition coil, stator, and timing specifications.
Lubrication System:
Two-stroke oil injection system (if applicable), gear oil specifications, and lubrication points.
Exhaust System:
Exhaust pipe, silencer, and reed valve assembly.
Transmission:
Gearbox disassembly, inspection, repair, clutch assembly, and operation.
Cooling System:
Air-cooling system, fin cleaning, and inspection.
Electrical System:
Wiring diagrams, lighting (if applicable), switches, fuses, and battery (if applicable).
Suspension Front:
Front fork disassembly, seal replacement, oil levels, damping adjustments, and spring specifications.
Suspension Rear:
Monoshock rear suspension, linkage, shock absorber service, and adjustment.
Brakes Front:
Hydraulic disc brake system, caliper service, master cylinder, brake pads, and fluid specifications.
Brakes Rear:
Hydraulic disc brake system, caliper service, master cylinder, brake pads, and fluid specifications.
Wheels And Tires:
Wheel bearing inspection and replacement, spoke tensioning, tire pressure, and fitment.
Frame And Bodywork:
Frame inspection, seat, fenders, handlebars, and control levers.
Routine Maintenance:
Oil changes, chain lubrication and adjustment, air filter cleaning, spark plug replacement.
Tune Ups:
Carburetor adjustment, ignition timing checks, and general performance optimization.
Troubleshooting:
Diagnostic procedures for common starting, running, and performance issues.
Disassembly And Assembly:
Detailed step-by-step instructions for component removal and installation.
Overhaul Procedures:
Comprehensive instructions for rebuilding major engine components and assemblies.
Inspection And Replacement:
Guidelines for inspecting wear and tear on parts and recommending replacement.
Special Tool Identification:
References to and illustrations of specialized tools required for specific tasks.
Depth Of Coverage:
In-depth technical information suitable for professional mechanics and experienced enthusiasts.
Safety Information:
Emphasis on safety precautions, warnings (WARNING, CAUTION, NOTE), and proper usage of tools and equipment.
Proprietary Components:
Includes instructions for proprietary Yamaha components and refers to manufacturer instructions for any third-party parts.
Engine Type:
Liquid-cooled, 2-stroke, reed-valve induction
Bore X Stroke:
Approx. 54.0 mm x 54.5 mm (varies slightly by year, check manual for specifics)
Compression Ratio:
Varies by year, typically around 9.5:1 - 10.5:1 (check manual)
Horsepower:
Approx. 35-40 HP (at crankshaft, varies by year and tuning)
Torque:
Not typically specified in typical marketing terms for this class of bike, but torque curve is key.
Carburetor Type:
Mikuni VM Series (e.g., VM28 or VM30, size varies by year)
Fuel Type:
Unleaded gasoline, 91 octane or higher recommended.
Oil Mixture:
Premix (50:1 ratio with high-quality 2-stroke oil) or Auto-lube system (check manual for specific year).
Spark Plug Type:
NGK BR8ES or equivalent (check manual for exact specification)
Transmission Type:
Constant-mesh 6-speed sequential
Clutch Type:
Wet, multi-disc, cable-actuated
Gear Ratios:
Specific gear ratios are detailed within the manual.
Transmission Oil Type:
Yamaha motorcycle gear oil (e.g., Yamalube Gear Oil) or equivalent SAE 80W API GL-4.
Transmission Oil Capacity
Transmission Oil Capacity:
Approx. 0.75 Liters (check manual for exact capacity and fill level).
Overall Length:
Varies by year, typically around 2160-2175 mm (85.0-85.6 in)
Overall Width:
Varies by year, typically around 800-825 mm (31.5-32.5 in)
Overall Height:
Varies by year, typically around 1270-1290 mm (50.0-50.8 in)
Dry Weight:
Approx. 94-97 kg (207-214 lbs) (varies by year)
Wet Weight:
Approx. 100-103 kg (220-227 lbs) (with all fluids, varies by year)
Wheelbase:
Varies by year, typically around 1440-1445 mm (56.7-56.9 in)
Ground Clearance:
Varies by year, typically around 350-360 mm (13.8-14.2 in)
Seat Height:
Varies by year, typically around 960-965 mm (37.8-38.0 in)
Oil Change Interval:
Refer to manual for specific hours or mileage, typically after every few rides or at specific hour marks (e.g., 10-20 hours).
Air Filter Cleaning:
Frequent cleaning recommended, especially in dusty conditions (after every few rides).
Spark Plug Replacement:
Inspect regularly, replace as needed based on performance and manual recommendations (e.g., every 20-40 hours).
Chain Lubrication Adjustment:
Lubricate and check tension before every ride.
Suspension Service:
Recommended fork oil changes and seal inspections at specified intervals (e.g., 20-40 hours) or as per manual.
Engine Oil Type:
High-quality 2-stroke premix oil (e.g., Yamalube 2R, Motul 800 2T Factory Line) at 50:1 ratio, or Yamaha's Auto-lube oil for the injection system if equipped.
Brake Fluid Type:
DOT 3 or DOT 4 hydraulic brake fluid.
Common Wear Items:
Clutch plates, piston and rings, brake pads, chain and sprockets, wheel bearings, suspension seals.
Engine Maintenance Focus:
Due to its 2-stroke nature, regular top-end rebuilds (piston, rings) are common maintenance items for optimal performance.