Segment:
Lightweight Dual-Sport / Motocross
Key Competitors Era:
Honda CR125R, Kawasaki KX125, Suzuki RM125, KTM 125 EXC (during its production run).
Vehicle Type:
Two-stroke, off-road focused motorcycle with street legality in some configurations.
Target Audience:
Enthusiasts seeking a capable and relatively simple-to-maintain off-road machine, often for trail riding and recreational use.
Engine Mechanical:
Engine disassembly, inspection, repair, and reassembly procedures for all internal components.
Engine Electrical:
Ignition system, charging system, starting system, CDI unit, wiring diagrams, troubleshooting electrical faults.
Fuel System:
Carburetor specifications, adjustments, cleaning, fuel tank, fuel lines, fuel filter.
Transmission Drivetrain:
Clutch operation and adjustment, gearbox internal inspection and repair, chain drive maintenance.
Suspension:
Front fork (telescopic) overhaul, rear shock absorber inspection and replacement, linkage lubrication.
Brakes:
Front and rear brake system inspection, hydraulic fluid replacement, pad and caliper maintenance, bleeding procedures.
Wheels Tires:
Wheel bearing inspection and replacement, tire pressure specifications, wheel balance checks.
Cooling System:
Radiator inspection, coolant specifications and capacity, water pump maintenance (if applicable).
Exhaust System:
Exhaust pipe and silencer inspection, gasket replacement.
Frame Bodywork:
Frame inspection, body panel removal and installation, seat, fenders, and fairings.
Electrical Wiring:
Complete wiring diagrams, component location, troubleshooting electrical issues.
Preventative Maintenance:
Routine checks, lubrication points, filter replacement intervals, spark plug service.
Troubleshooting:
Diagnostic procedures for common problems, symptom-based troubleshooting guides.
Repair Overhaul:
Detailed step-by-step instructions for component disassembly, repair, and reassembly.
Adjustment Calibration:
Carburetor, clutch, and throttle cable adjustments.
Specifications Data:
Torque specifications, clearances, fluid capacities, electrical component values.
Depth:
Comprehensive, from basic maintenance to full engine and gearbox rebuilds.
Engine Type:
Liquid-cooled, 2-stroke, reed valve
Bore X Stroke:
56.0 mm x 50.7 mm (typical for DT125 variants)
Compression Ratio:
Approx. 7.5:1 (typical for this era, varies with specific tuning)
Horsepower:
Approx. 23-25 HP (at crank, figures vary by market and tuning)
Torque:
Approx. 20-22 Nm (at crank, figures vary)
Carburetor:
Mikuni VM28 (common fitment for DT125 series)
Fuel Type:
Unleaded gasoline (minimum 91 octane recommended), requires pre-mix oil
Oil Mixing:
Autolube system (separate oil injection tank)
Length:
Approx. 2120 mm (varies slightly)
Width:
Approx. 825 mm (varies slightly)
Height:
Approx. 1205 mm (varies slightly)
Seat Height:
Approx. 865 mm (varies)
Wheelbase:
Approx. 1420 mm
Dry Weight:
Approx. 107 kg (varies by market/configuration)
Wet Weight:
Approx. 118 kg (with fluids, estimated)
Crash Safety:
N/A (Motorcycle safety ratings differ from automobiles; primary safety relies on rider skill and adherence to traffic laws).
Braking System:
Disc brakes front and rear.
Lighting:
Headlight, taillight, turn signals (street-legal variants).
Frame Construction:
Steel perimeter frame for rigidity and durability.
Oil Change:
Refer to manual for gearbox oil change interval (typically every 3,000-5,000 km or annually).
Spark Plug Service:
Check and clean/replace every 3,000-4,000 km or as needed.
Air Filter Cleaning:
Clean every 1,000-2,000 km or more frequently in dusty conditions.
Chain Lubrication Adjustment:
Lubricate every 500 km and adjust slack as needed (typically 20-30mm).
Gearbox Oil:
Yamaha Motorcycle Gear Oil (GL-4) or equivalent, SAE 10W-30 or 10W-40. Capacity: Approx. 1.0-1.2 Liters.
Coolant:
Yamaha Performance Coolant or equivalent mixture of ethylene glycol and distilled water (50/50). Capacity: Approx. 0.8 Liters.
Brake Fluid:
DOT 3 or DOT 4 brake fluid.
2-Stroke Oil:
High-quality 2-stroke motorcycle oil (e.g., Yamalube 2M) for the Autolube system.
Carburetor Tuning:
Can be sensitive to altitude and temperature changes; requires periodic fine-tuning for optimal performance.
Power Valve Sticking:
Carbon buildup can cause the power valve to stick, affecting engine response. Requires periodic cleaning.
Suspension Seals:
Front fork seals can wear over time, leading to leaks, especially with aggressive off-road use.
Electrical Connections:
Corrosion or loose connections can cause intermittent electrical issues, particularly in humid or wet environments.
Yamaha Motorcycles:
Yamaha Motor Company is renowned for its innovation in motorcycles, particularly in off-road and racing segments, with a long history dating back to the 1950s.
Dt Series Legacy:
The DT series is a long-standing Yamaha line of dual-sport motorcycles, known for their durability and off-road capability, evolving from the original DT-1.
Manufacturing Location:
Primarily Japan, though specific assembly locations could vary by market.
