Market Position:
The Yamaha DT125RE/X represents a significant entry in the lightweight dual-sport and supermoto categories, appealing to riders seeking nimble handling, off-road capability (RE), or on-road sportiness (X) with a classic 2-stroke engine character.
Competitors:
Competes with other 125cc off-road and dual-sport motorcycles from manufacturers like Honda (CRF125F, XR125), Suzuki (DR-Z125), Kawasaki (KLX125), and KTM (125 EXC).
Engine Type:
2-stroke, liquid-cooled, single-cylinder
Suspension Design:
Telescopic front forks, Monocross rear suspension system.
Braking System:
Disc brakes front and rear.
Systems Covered:
Engine, Fuel System, Carburetion, Ignition System, Electrical System, Chassis, Suspension (Front & Rear), Brakes (Front & Rear), Wheels & Tires, Frame, Bodywork, Cooling System, Exhaust System, Transmission, Drivetrain, Troubleshooting, Specifications, Diagrams
Estimated Page Count:
Hundreds of pages
Manual Type:
Factory Service Repair Manual
Engine:
Detailed breakdown of the 125cc 2-stroke engine, including top-end and bottom-end rebuild procedures, piston, rings, cylinder, crankshaft, bearings, seals, and gaskets.
Fuel System:
Comprehensive coverage of the fuel tank, fuel lines, fuel pump (if applicable), and carburetor system. Includes cleaning, adjustment, and overhaul procedures for the carburetor (likely Mikuni VM series).
Ignition System:
Details on the CDI (Capacitor Discharge Ignition) system, including ignition timing, spark plug specifications, stator, and coil testing and replacement.
Electrical System:
Wiring diagrams, component testing (lights, horn, indicators, battery, starter), troubleshooting electrical faults, and fuse specifications.
Chassis Suspension:
Front and rear suspension disassembly, inspection, maintenance, and adjustment. Includes fork seals, oil levels, spring rates, and rear shock absorber service.
Brakes:
Front and rear brake system maintenance, including hydraulic systems (if applicable), disc brake pad replacement, caliper service, brake fluid flush and bleed, and drum brake adjustment.
Wheels Tires:
Wheel bearing inspection and replacement, spoke tensioning and truing, tire mounting and balancing, and recommended tire pressures.
Frame Bodywork:
Frame inspection for damage, removal and installation of body panels, seat, fuel tank, and handlebars.
Maintenance:
Regular service checks, lubrication points, filter replacements (air, oil - if applicable), spark plug checks, chain adjustment and lubrication, brake adjustments.
Troubleshooting:
Diagnostic procedures for common problems such as starting issues, poor performance, overheating, electrical faults, and brake problems.
Repair:
Step-by-step instructions for component disassembly, overhaul, reassembly, and replacement for all major systems.
Diagnostics:
Detailed diagnostic flowcharts and explanations for identifying and resolving mechanical and electrical issues.
Depth:
Comprehensive, covering basic user maintenance to advanced engine rebuilds and electrical diagnostics. Suitable for professional mechanics and experienced DIY enthusiasts.
Engine Type:
2-stroke, reed valve, liquid-cooled, single cylinder
Bore X Stroke:
56.5 mm x 50.7 mm
Compression Ratio:
7.5:1 (typical for this era and engine type)
Power Output Hp:
Approximately 15-17 hp at 8000-8500 rpm (varies slightly by market and specific tuning)
Torque Nm:
Approximately 13-14 Nm at 7000-7500 rpm
Top Speed:
Approximately 110-120 km/h (68-75 mph)
Carburetor Model:
Mikuni VM26 (typical, specific model may vary slightly)
Fuel Type:
Unleaded gasoline, 91 octane or higher recommended
Oil Mixing:
Pre-mix or Autolube system (Yamaha's Yamalube 2-stroke oil recommended)
Transmission Type:
6-speed constant mesh
Clutch Type:
Wet, multiple-disc
Gear Ratios:
Specific gear ratios detailed within the manual (e.g., 1st: 2.833, 2nd: 1.875, 3rd: 1.381, 4th: 1.143, 5th: 0.955, 6th: 0.833)
Transmission Oil Type:
Yamaha Genuine Gear Oil or equivalent API GL-4, SAE 80W
Length:
Approximately 2140 mm (DT125RE), 2075 mm (DT125X)
Width:
Approximately 805 mm (DT125RE), 800 mm (DT125X)
Height:
Approximately 1170 mm (DT125RE), 1145 mm (DT125X)
Seat Height:
Approximately 885 mm (DT125RE), 850 mm (DT125X)
Wheelbase:
Approximately 1405 mm (DT125RE), 1385 mm (DT125X)
Dry Weight:
Approximately 122 kg (DT125RE), 120 kg (DT125X)
Fuel Capacity:
10 Liters (2.6 US gal)
Oil Tank Capacity:
1.4 Liters (Autolube system)
Safety Ratings:
Not typically rated by formal automotive safety organizations like NHTSA or Euro NCAP as it is a motorcycle.
Braking System:
Front and rear disc brakes provide reliable stopping power.
Lighting:
Headlight, taillight, brake lights, and turn signals for visibility.
Frame Construction:
Robust steel frame designed for durability and handling.
Ergonomics:
Designed for comfortable rider control and feedback.
Oil Change Transmission:
Every 6,000 km or 1 year (whichever comes first)
Spark Plug Check:
Every 3,000 km or 6 months
Air Filter Cleaning:
Every 3,000 km or 6 months, or more frequently in dusty conditions
Chain Cleaning Lubrication:
Every 1,000 km or 1 month, or after riding in wet conditions
Brake Fluid Check:
Every 6,000 km or 1 year
Engine Oil Type 2Stroke:
Yamaha Yamalube 2 Stroke Oil or equivalent API TC, JASO FD certified, SAE 10W-30
Cooling System Coolant:
Yamaha Yamalube Coolant (50% ethylene glycol and 50% deionized water mixture)
Common Issues:
Common issues for 2-stroke 125cc engines of this era can include wear on the piston and cylinder due to high operating temperatures and stress, potential clutch wear, carburetor jetting sensitivity to altitude and temperature, and exhaust power valve maintenance (if equipped).
Yamaha Heritage:
Yamaha has a long and storied history in motorcycle manufacturing, particularly with its 2-stroke off-road and dual-sport motorcycles, dating back to the legendary DT series.
Dt Series Evolution:
The DT125 lineage has evolved significantly over decades, with the RE and X models representing later iterations, incorporating modern technology and design refinements while retaining the core 2-stroke performance.
Production Period:
The DT125 platform has seen various iterations produced globally for many years prior to and beyond the 2002-2008 period, reflecting its enduring popularity.
