Vehicle Segment:
Lightweight scooter, utility/commuter segment
Competitors:
Honda Lead 125, Suzuki Address 125, Kymco Agility 125, SYM Jet 125 (depending on specific market)
Design Purpose:
Designed for urban commuting, providing a balance of fuel efficiency, maneuverability, and reliability.
Manual Purpose:
Essential resource for all maintenance, repair, and diagnostic needs for the Yamaha YJ125, ensuring longevity and optimal performance.
Years Covered:
2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
Estimated Pages:
Hundreds (exact count varies, but substantial)
Type:
Workshop Service Repair Manual
Engine Systems:
Engine disassembly, assembly, inspection, tuning, lubrication, cooling, fuel, ignition, exhaust, starting, charging
Transmission Drivetrain:
Transmission operation, inspection, repair, final drive, clutch
Chassis Suspension:
Frame, front fork, rear shock absorber, swingarm, wheel bearings, steering
Braking System:
Brake system maintenance, inspection, repair, bleeding, component replacement (discs, pads, calipers, master cylinders)
Electrical System:
Wiring diagrams, battery, charging system (alternator/stator, rectifier/regulator), ignition system, lighting, instrumentation, starter motor
Fuel System:
Carburetor disassembly, cleaning, adjustment, fuel pump, fuel tank, fuel lines
Body And Trim:
Body panel removal/installation, seat, fairings, fenders, trim pieces
Maintenance Procedures:
Routine maintenance, oil changes, filter replacements, spark plug service, chain adjustment, brake pad inspection/replacement, tire pressure checks
Troubleshooting Guides:
Systematic diagnostics for common and uncommon issues, fault finding charts
Repair Procedures:
Step-by-step instructions for component disassembly, repair, and reassembly
Overhaul Procedures:
Detailed instructions for engine and transmission overhauls
Wiring Diagrams:
Comprehensive electrical schematics for all systems
Depth Level:
Comprehensive factory-level detail, suitable for professional technicians and experienced DIY enthusiasts
Engine Type:
Four-stroke, air-cooled, SOHC
Displacement:
Approximately 125cc (Specific bore and stroke figures detailed in manual)
Bore X Stroke:
Refer to manual for precise dimensions
Compression Ratio:
Refer to manual for specific ratio
Horsepower:
Typically in the 8-10 HP range (exact figures vary by market and tuning)
Torque:
Torque figures available in manual for optimal tuning
Carburetor Type:
CV (Constant Velocity) carburetor, specific model detailed in manual (e.g., Mikuni VM series)
Fuel Type:
Unleaded gasoline
Fuel Capacity:
Approximately 5-6 Liters (specific capacity detailed in manual)
Overall Length:
Refer to manual for exact dimensions
Overall Width:
Refer to manual for exact dimensions
Overall Height:
Refer to manual for exact dimensions
Dry Weight:
Approx. 100-110 kg (Specific figures in manual)
Curb Weight:
Refer to manual for precise curb weight
Safety Standards:
Complies with applicable safety regulations for its class in various markets. Specific certifications not typically detailed in service manuals but implicit in design.
Braking System:
Disc front brake, drum rear brake (common configuration; check manual for variations). ABS typically not present on this model.
Lighting:
Headlight, taillight, brake light, turn signals for visibility.
Instrument Cluster:
Analog speedometer, fuel gauge, odometer, trip meter, indicator lights (turn signals, oil, high beam). Specific cluster design may vary.
ABS:
Anti-lock Braking System (ABS) is typically not a feature on this model.
Charging Ports:
12V accessory socket (optional or standard depending on market/trim) for charging devices is possible, but not standard on all models. Manual may show wiring for this.
Oil Change Interval:
Refer to manual for specific mileage/time interval (e.g., every 3,000-5,000 km or annually).
Air Filter Cleaning Replacement:
Refer to manual for specific interval.
Spark Plug Replacement:
Refer to manual for specific interval.
Engine Oil Type:
Yamalube (or equivalent) SAE 10W-30 or 20W-40 API SG or higher, JASO MA recommended. Specific viscosity based on ambient temperature is detailed in the manual.
Engine Oil Capacity:
Refer to manual for exact capacity (e.g., ~0.8-1.0 liters).
Brake Fluid Type:
DOT 3 or DOT 4 (refer to manual for specific recommendation and replacement intervals).
Gear Oil Type:
Refer to manual for specific gear oil specification and capacity (typically API GL-3 or GL-4).
Common Wear Items:
Tires, brake pads, drive belt, spark plugs, air filter, battery. Manual provides wear limits and replacement procedures.
Carburetor Issues:
Can be prone to gumming if fuel sits; requires periodic cleaning and adjustment. Manual details proper cleaning procedures.
Yamaha History:
Yamaha Motor Company, established in 1955, has a rich history in manufacturing motorcycles, scooters, and marine products, known for innovation and performance.
Yj125 Lineage:
The YJ125 is part of Yamaha's scooter lineup, evolving from earlier models to meet commuter demands. Specific evolution details are not typically in a single service manual but implied by the model generation.
Manufacturing Location:
Typically manufactured in Asia (specific country may vary by market, e.g., Indonesia, Taiwan, China).
