Segment:
Lightweight Dual-Sport / Motocross
Competitors:
KTM EXC series, Honda CR/XR series, Kawasaki KDX series, Suzuki RM series.
Model Focus:
The DT125 series represents Yamaha's enduring commitment to the 125cc class, offering robust performance and off-road capability in a user-friendly package. The RE and X variants likely cater to slightly different street-legal and off-road focused configurations.
Engine:
Engine overhaul, top-end (cylinder, piston, rings), bottom-end (crankshaft, connecting rod, bearings), lubrication system, cooling system (if applicable), fuel system (carburetor, intake), exhaust system.
Transmission:
Gearbox operation, clutch, shift mechanism, lubrication, troubleshooting.
Chassis:
Frame, swingarm, suspension (forks, shock absorber), steering system, wheels, bearings.
Brakes:
Front and rear brake systems (disc brakes likely), hydraulic components, fluid replacement, bleeding, pad/shoe replacement.
Electrical System:
Ignition system, lighting, charging system (stator, rectifier/regulator), battery, starting system, wiring diagrams, component testing.
Fuel System:
Carburetor tuning, cleaning, jetting, fuel lines, fuel tank maintenance.
Bodywork:
Fairings, fenders, seat, handlebars, controls, fasteners.
Maintenance:
Scheduled maintenance, oil changes, filter replacements, chain adjustment, lubrication points, spark plug replacement, air filter cleaning/replacement.
Troubleshooting:
Diagnostic charts for common problems, symptom-based troubleshooting for engine, electrical, and mechanical issues.
Repair:
Step-by-step repair instructions for all major components, including disassembly, reassembly, and torquing specifications.
Diagnostics:
Basic diagnostic procedures, component testing methods.
Depth:
Comprehensive, from basic owner maintenance to complete engine and chassis rebuilds.
Type:
2-stroke, liquid-cooled, reed valve induction
Displacement:
124 cc (approximate, specific variants may differ slightly)
Bore X Stroke:
56.5 mm x 50.2 mm (typical for this era DT125)
Compression Ratio:
Approximately 7.2:1 to 8.0:1 (varies by specific model variant)
Horsepower:
Approximately 15-18 HP (street-legal variants), higher for off-road focused models.
Torque:
Approximately 12-15 Nm (varies by model variant)
Carburetor:
Mikuni VM28 (typical for DT125RE/X)
Fuel Type:
Unleaded gasoline (91 octane or higher recommended)
System:
Autolube (premix system for 2-stroke oil)
Type:
CDI (Capacitor Discharge Ignition)
Overall Length:
Approx. 2150 mm (varies by model)
Overall Width:
Approx. 800 mm (varies by model)
Overall Height:
Approx. 1200 mm (varies by model)
Dry Weight:
Approx. 115-125 kg (varies by model)
Wet Weight:
Approx. 125-135 kg (varies by model)
Fuel Tank Capacity:
10.0 Liters (approx.)
Oil Tank Capacity:
1.0 Liters (approx.) for Autolube system
Crash Tests:
N/A (Motorcycle - manufacturer-specific safety design)
Braking System:
Front disc brake, Rear disc brake (common for RE/X variants). ABS not standard.
Lighting:
Headlight, taillight, brake light, turn signals (street-legal variants).
Features:
Basic analog instrumentation (speedometer, tachometer, odometer, trip meter, engine warning light, turn signal indicators).
Features:
N/A (Focus on core mechanical and electrical systems).
Oil Change:
Every 3,000-5,000 km or annually (transmission oil). Check owner's manual for specifics.
Spark Plug Replacement:
Every 5,000-8,000 km or as needed based on inspection.
Air Filter Cleaning:
Every 2,000-3,000 km or more frequently in dusty conditions.
Chain Lubrication:
Every 500-1,000 km or after riding in wet conditions.
Engine Oil:
Yamalube 2-stroke oil or equivalent API TC, JASO FD approved oil.
Transmission Oil:
Yamalube Gear Oil 10W-40 or equivalent SAE 80 hypoid gear oil.
Brake Fluid:
DOT 4 hydraulic brake fluid.
Coolant:
Yamaha's recommended permanent type coolant or equivalent ethylene glycol-based coolant with anti-rust inhibitors.
Common Problems:
Carburetor gumming if not run regularly, exhaust power valve sticking (on some earlier models, but may be present), clutch wear, fork seal leaks, electrical connector corrosion in wet environments.
Preventative Maintenance:
Regular cleaning of the carburetor, use of quality 2-stroke oil, proper chain maintenance, and ensuring electrical connections are clean and sealed.
Heritage:
Yamaha has a long and storied history in off-road and dual-sport motorcycles, with the DT lineage dating back decades, known for their reliability and versatility.
Evolution:
The DT125 platform has seen continuous updates, with the 2002-2008 models representing a more modern iteration, likely incorporating improvements in engine emissions, suspension, and braking compared to earlier generations. The RE and X suffixes typically indicate variations for road legality and off-road focus respectively.
Manufacturing Locations:
Primarily Japan, with potential assembly in other regions.
