The DT125R, produced in 1988, is a capable dual-sport motorcycle renowned for its robust two-stroke engine and agile off-road capabilities. This model builds upon a strong heritage in off-road and racing motorcycles, offering a blend of durability and performance that made it a popular choice for trail riding and light off-roading. Its design emphasizes simplicity for ease of maintenance, coupled with features like the Power Valve System for enhanced power delivery, and a reliable chassis built for resilience in varied terrain. This comprehensive factory service repair manual provides in-depth guidance for the 1988 DT125R. It covers all essential aspects of maintenance and repair, including detailed procedures for engine disassembly and assembly, fuel and ignition system servicing, transmission overhauls, suspension and brake maintenance, and electrical system diagnostics. The manual includes crucial technical specifications, torque values, fluid recommendations, troubleshooting guides, and clear wiring diagrams, empowering owners and technicians to effectively maintain, repair, and optimize the performance of this classic dual-sport motorcycle. 🏷️ Basic Information Identification Make: Yamaha Model: DT125R Year: 1988 Vehicle Type: Dual-Sport Motorcycle 👋 Introduction Market Position Market Segment: Entry-level to intermediate dual-sport motorcycle, popular for trail riding, light off-roading, and commuting. Competitive Analysis Competitors 1988: Honda XL series, Kawasaki KLR250, Suzuki DR200/DR250. Key Features Durability: Yamaha's reputation for robust two-stroke engines and reliable chassis components. Off Road Capability: Designed with off-road prowess featuring long-travel suspension and durable construction. Simplicity: Relatively simple mechanical design for ease of maintenance and repair. 📋 Manual Details Coverage Areas Coverage Summary: Comprehensive factory service and repair for Yamaha DT125R 1988 model. Page Count Estimated Pages: Hundreds (specific count not provided, but described as complete). Manual Type Type: Factory Service Repair Manual Language Language: English (assumed based on typical factory manuals for international markets). Format Format: Downloadable PDF 📖 Manual Coverage Systems Covered Engine: Complete engine disassembly, assembly, tuning, troubleshooting, and repair for the 125cc two-stroke engine. Fuel System: Carburetor (Mikuni VM series likely) disassembly, cleaning, adjustment, and troubleshooting; fuel tank and petcock inspection and repair. Ignition System: CDI ignition system, spark plug selection and gap, coil testing, timing procedures. Transmission: Six-speed gearbox overhaul, clutch adjustment and replacement, gearshift mechanism. Suspension: Front telescopic forks (likely KYB or similar) service, oil change, seal replacement, damping adjustment; rear Monoshock suspension (Monocross system) rebuild and adjustment. Brakes: Front and rear drum brakes (typical for this era and model) inspection, adjustment, and relining; hydraulic disc brake service if applicable to specific regional variants (though less likely for base 1988 R model). Electrical System: Wiring diagrams, lighting system, charging system (stator, regulator/rectifier), battery maintenance, starter motor (if electric start equipped), horn, indicators. Cooling System: Air-cooled engine specifications and maintenance. Exhaust System: Expansion chamber maintenance, mufflers, and performance tuning considerations. Frame And Bodywork: Chassis inspection, steering head bearing service, body panel removal and installation, seat maintenance. Procedures Included Routine Maintenance: Oil changes, filter replacements (air, spark plug), chain adjustment, lubrication points. Troubleshooting: Diagnostic procedures for common performance issues, starting problems, electrical faults. Repair Procedures: Step-by-step guides for major component overhauls and component replacements. Specifications Charts: Torque specifications, clearances, fluid capacities, electrical resistance values. Wiring Diagrams: Detailed, color-coded wiring diagrams for electrical system diagnostics and repair. Special Tools: Identification and usage of specialized tools required for certain procedures. Technical Depth Depth: Full factory level, covering everything from basic maintenance to complete engine and chassis rebuilds. 📊 Manual Specifications File Format Format: PDF (Portable Document Format) Print Quality Quality: High-resolution scans of original factory documentation, allowing for clear printing of text and diagrams. Binding Type Binding: N/A (Digital Download) Paper Type Paper Type: N/A (Digital Download) Searchability Text Search: Likely text-searchable if OCR was applied during PDF creation, enhancing ease of navigation. Printability Printable: Yes, pages can be printed individually or in full as needed. ⚙️ Engine Specifications Primary Engine Engine Type: 123cc liquid-cooled, 2-stroke, reed valve inducted, single-cylinder. Bore X Stroke: 56.0 mm x 50.0 mm (typical for DT125R). Compression Ratio: Approx. 7.2:1 (varies with tuning). Power Output Hp: Approx. 22-25 HP @ 8000 RPM (typical for 1988 model, varies by region). Torque Lb-Ft: Approx. 15-17 lb-ft @ 7000 RPM (typical). Performance Top Speed Mph: 70-75 mph (estimated). Fuel System Carburetor Model: Mikuni VM28SS (likely, standard fitment). Fuel Type: Unleaded gasoline, minimum 87 octane (Octane rating may vary based on regional fuel standards). Fuel Mixture: Pre-mix gasoline and 2-stroke oil (ratio typically 50:1 or 100:1 depending on oil quality and manufacturer recommendation). 🔧 Transmission Standard Type: Constant mesh, 6-speed sequential return. Clutch Type: Wet, multiple disc. Features Gear Ratios: Specific ratios available in the manual, crucial for performance tuning. Final Drive: O-ring sealed chain drive (specific sprocket sizes will be detailed). 📐 Dimensions Exterior Length: Approx. 2170 mm (85.4 in). Width: Approx. 810 mm (31.9 in). Height: Approx. 1155 mm (45.5 in). Wheelbase: Approx. 1420 mm (55.9 in). Weights Dry Weight: Approx....