This manual covers the 125cc two-stroke racing motorcycle produced from 1990 to 2005. The extensive motorsport heritage is evident in the series, a cornerstone of 125cc Grand Prix programs, known for its competitive pedigree and continuous development. The 125 has been a successful platform in national and international racing, showcasing its engineering quality and reliability for demanding track use. This particular iteration, the G1, represents a specific development within the lineage, designed for riders and mechanics seeking peak performance and precision on the race circuit. This comprehensive Factory Service Repair Workshop Manual provides in-depth information for the maintenance, repair, and troubleshooting of your G1. It covers all essential systems, including the engine, transmission, fuel, cooling, electrical, and chassis components, offering step-by-step instructions, detailed diagrams, and exploded views. The manual is designed for owners with basic mechanical skills, as well as independent service professionals and authorized technicians, enabling them to perform everything from routine checks and adjustments to full engine rebuilds and advanced diagnostics. This resource ensures your 125 is maintained to factory specifications, maximizing its performance and longevity. 🏷️ Basic Information Identification Make: Yamaha Model: TZ125 Model Variant: TZ125G1 Production Years Covered: 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 Generation Generation Code: G1 👋 Introduction Market Position Target Audience: Owners with basic mechanical skills, independent service professionals, and authorized dealer service departments. Value Proposition: Provides factory-level repair and maintenance information to save money and ensure proper upkeep. Key Features Instruction Style: Step-by-step instructions, clear and concise text, supported by diagrams and illustrations. Accuracy: Vehicle-specific information, not generic; same procedures used by authorized technicians. Completeness: Complete and intact, covering all major topics without missing or corrupt parts. 📋 Manual Details Coverage Areas Primary Coverage: Service, Repair, Maintenance, Troubleshooting, Diagnostics Specific Topics: General information, Routine Maintenance, Specifications, Periodic checks and adjustments, Lubrication, Cooling System, Transmission, Drive Chain, Sprockets, Engine Specifications, Engine Removal and Installation, Fuel system, Steering System, Shocks, Body Work, Intake & Exhaust, Electrical system, Advanced Troubleshooting, Wiring Diagram Page Count Estimated Page Count: Varies, typically comprehensive for workshop manuals of this era (estimate 300-500 pages based on content listed) Manual Type Manual Type: Factory Service Repair Workshop Manual Language Language: English Format File Format: PDF 📖 Manual Coverage Systems Covered Engine System: Complete overhaul, disassembly, assembly, tuning, troubleshooting, specifications, cooling system, lubrication. Transmission System: Gearbox inspection, repair, maintenance, lubrication, gear ratios, removal and installation. Chassis Suspension Steering: Front and rear suspension systems, shock absorber service and adjustment, steering head bearing maintenance, steering system components. Fuel System: Carburetor tuning, cleaning, and overhaul, fuel tank maintenance, fuel lines, fuel pump (if applicable). Electrical System: Ignition system, lighting, charging system, wiring diagrams, component testing, troubleshooting. Bodywork Frame: Body panel removal and installation, fairings, seat, handlebars, general inspection. Braking System: Brake caliper service, brake fluid replacement, brake line inspection, master cylinder maintenance. Drive Train: Drive chain adjustment, lubrication, sprocket replacement, maintenance. Procedures Included Maintenance Procedures: Oil changes, filter replacements, spark plug service, chain adjustments, lubrication points, air filter cleaning/replacement. Repair Procedures: Engine rebuild, transmission overhaul, suspension component replacement, electrical component repair, bodywork repair. Troubleshooting Diagnostics: Step-by-step diagnostic procedures for common and uncommon issues, symptom-based troubleshooting guides. Assembly Disassembly: Detailed instructions for removing and installing major components like the engine, transmission, suspension, and body panels. Technical Depth Depth Of Information: Comprehensive, covering basic maintenance to full engine and transmission rebuilds, including advanced electrical diagnostics. Diagrams Illustrations: Includes detailed diagrams, illustrations, and exploded views for clarity. Schematics: Comprehensive wiring schematics for electrical system diagnosis and repair. 📊 Manual Specifications File Format File Type: PDF Print Quality Printability: Yes, all pages are printable. Digital Viewing: Viewable on PC, Mac, phones, and ebook readers (e.g., Kindle). Binding Type Binding: N/A (Digital PDF download) Paper Type Paper Quality: N/A (Digital PDF download - user prints as needed) ⚙️ Engine Specifications Primary Engine Engine Type: Two-stroke, single-cylinder (This is typical for TZ125, specific details would be in the manual). Displacement: 125cc (This is inferred from the model name 'TZ125'). Performance Horsepower Range: Typical for 125cc racing engines of this era: 35-45 HP (Specifics in manual). Torque Range: Low to mid-range, focused on peak power delivery (Specifics in manual). Fuel System Fuel Delivery: Carburetor(s) (Likely Mikuni VM series, specific model in manual). Ignition System Ignition Type: CDI (Capacitor Discharge Ignition) (Typical for this era). Cooling System Cooling Method: Liquid-cooled (Typical for TZ race bikes). 🔧 Transmission Standard Transmission Type: 6-speed constant mesh sequential (Standard for TZ125). Optional Optional Gearbox: N/A (Race bikes typically had fixed configurations, though factory options might exist). Features Clutch Type: Wet, multi-disc (Standard for this type of motorcycle). 📐 Dimensions Weights Dry Weight: Approximately 75-80 kg (Typical for TZ125). Wet Weight: Varies with fluids, estimate ~85 kg (Specifics in manual). Capacities Fuel Tank Capacity: Typically around 10-12 liters...