The DT125 and DT125R, produced for the 1987 and 1988 model years, represent a lineage of reliable and capable lightweight dual-sport motorcycles. Known for their robust two-stroke, single-cylinder engines and strong off-road prowess, these models offered a versatile riding experience suitable for both trails and general use. With a focus on durability and straightforward engineering, the DT series has a well-earned reputation for providing dependable performance, making it a popular choice for riders seeking adventure and accessibility. This comprehensive workshop service repair manual provides detailed guidance for the maintenance and repair of the DT125 / DT125R. It covers a wide array of systems, including complete engine overhauls, fuel and transmission systems, chassis and suspension components, braking, and the electrical system. The manual includes step-by-step procedures for routine maintenance, engine rebuilds, carburetor tuning, and troubleshooting, offering in-depth technical specifications and wiring diagrams. This resource is designed to assist owners, mechanics, and technicians in preserving the longevity and optimal performance of their vehicles. 🏷️ Basic Information Identification Make: Yamaha Model: DT125 / DT125R Years Covered: 1987, 1988 Codes Engine Code Indicator: DT125, DT125R 👋 Introduction Market Position Vehicle Segment: Lightweight Dual-Sport / Enduro Motorcycle Competitive Analysis Key Competitors Era: Honda CR125R, Kawasaki KX125, Suzuki RM125 (motocross variants); various enduro machines. Key Features Dt125R Reputation: Known for its reliability, off-road capability, and relatively simple yet effective two-stroke engine. Manual Utility Value Proposition: Essential resource for owners and mechanics to maintain and repair the DT125/DT125R, ensuring longevity and optimal performance. 📋 Manual Details Coverage Areas Manual Scope: Workshop Service Repair Page Count Estimated Pages: Hundreds (as per description) Manual Type Manual Classification: Factory Official Full Service Repair Manual Language Primary Language: English Format Delivery Format: PDF Download 📖 Manual Coverage Systems Covered Engine System: Complete overhaul, diagnostics, tuning, lubrication, cooling, exhaust. Fuel System: Carburetor identification, adjustment, cleaning, fuel tank, fuel lines, petcock. Transmission System: Gearbox operation, clutch, shift mechanism, lubrication, repair procedures. Chassis Frame: Frame inspection, alignment, swingarm, pivot bearings, steering head bearings. Suspension Front: Front fork disassembly, assembly, oil change, seal replacement, spring rates. Brakes Front: Disc brake caliper servicing, hydraulic lines, master cylinder, pad replacement, bleeding. Electrical System: Ignition system, lighting, charging system (stator, regulator/rectifier), battery, wiring diagrams. Cooling System: Air cooling (fins), component checks. Exhaust System: Muffler, pipe inspection, sealing. Wheels Tires: Wheel bearing maintenance, spoke tensioning, tire pressure specifications. Bodywork Plastics: Fairing, fenders, seat, fuel tank removal and installation. Suspension Rear Rear Shock ABSorber: Monoshock unit service, linkage maintenance, damping adjustments. Brakes Rear Rear Brake System: Drum brake inspection, adjustment, shoe replacement. Procedures Included Routine Maintenance: Oil changes, filter replacements, chain adjustment, spark plug checks, air filter cleaning. Engine Rebuild: Top-end overhaul, piston, rings, cylinder, crankshaft service. Carburetor Tuning: Jetting, idle speed, mixture adjustments for optimal performance. Troubleshooting Diagnostics: Systematic fault finding for common and complex issues. Wiring Diagrams: Detailed electrical schematics for accurate diagnosis and repair. Component Disassembly Assembly: Step-by-step guides for all major motorcycle components. Technical Depth Diagnostic Capability: Advanced diagnostics and troubleshooting for intricate issues. Repair Complexity: Covers everything from basic adjustments to complete engine and chassis overhauls. Completeness: Full factory specification for comprehensive repair and maintenance. 📊 Manual Specifications File Format Document Format: PDF Print Quality Digital Resolution: High resolution, suitable for printing. Binding Type Digital Print Option: Printable in its entirety or specific sections. Paper Type Digital Paper Equivalent: N/A (Digital File) ⚙️ Engine Specifications Primary Engine Engine Type: Two-Stroke, Single-Cylinder Displacement: 123 cc (7.5 cubic inches) Bore X Stroke: 56.4 mm x 50.0 mm (approximate) Compression Ratio: Approx. 7.2:1 (varies slightly by model revision) Cooling System: Forced Air Cooling Ignition System: CDI (Capacitor Discharge Ignition) Spark Plug Type: NGK B8ES (or equivalent, consult manual for specific) Performance Horsepower Estimated: Approx. 17-20 HP (at crankshaft, varies by market and tuning) Torque Estimated: Approx. 14-16 Nm (at crankshaft, varies by market and tuning) Fuel System Carburetor Model: Mikuni VM26SS (typical for this era) Fuel Type: Unleaded Gasoline (min. 91 RON / 87 AKI recommended) Oil Mixture Ratio: 50:1 (2-stroke oil to gasoline in the oil injection system) 🔧 Transmission Standard Transmission Type: 6-Speed Constant Mesh Features Clutch Type: Wet, Multi-Plate Final Drive: Chain Drive (O-ring sealed type typical) 📐 Dimensions Exterior Overall Length: Varies by specific model variant, consult manual for exact figures. Weights Dry Weight Estimated: Approx. 100-110 kg (220-242 lbs) Fuel Tank Capacity: Approx. 9.5 - 10.5 Liters (2.5 - 2.8 Gallons) 🛡️ Safety Features Ratings Crash Safety Standards: N/A (Motorcycle, not subjected to automotive crash ratings) Active Features Braking System: Front Disc Brake, Rear Drum Brake for effective stopping power. Passive Features Frame Construction: Steel Frame providing structural integrity. 💡 Technology Features Infotainment Instrument Cluster: Analog speedometer, tachometer, and basic indicator lights (neutral, turn signals, high beam). Driver Assistance ABS Availability: Not equipped with ABS. Connectivity Connectivity Features: N/A (No modern electronic connectivity...