The Yamaha QT50, produced from 1979 to 1992, is a lightweight, step-through moped designed for urban commuting and recreational use. This iconic model, known for its user-friendliness and affordability, was a popular choice in its segment, competing with other 50cc two-stroke mopeds of the era. Engineered with a reliable air-cooled, two-stroke engine and an automatic Continuously Variable Transmission (CVT), the QT50 offers a smooth and accessible riding experience. Its robust steel frame and practical design, including ample ground clearance and a manageable wet weight, contribute to its enduring appeal among enthusiasts and owners. This comprehensive workshop service manual provides in-depth technical information for the Yamaha QT50, covering all model years from 1979 to 1992. The manual details engine overhaul, transmission servicing, chassis maintenance, brake system repair, and electrical diagnostics, including wiring diagrams. It also outlines routine maintenance procedures, troubleshooting guides for common issues such as carburetor clogging and CVT belt wear, and essential technical specifications. This resource is invaluable for owners, mechanics, and technicians seeking to maintain, repair, and preserve the performance and longevity of their Yamaha QT50. 🏷️ Basic Information Identification Make: Yamaha Model: QT50 Model Designation: QT 50 Model Code: QT50 Generation Production Start Year: 1979 Production End Year: 1992 Codes Chassis Code Prefix: 2T0 👋 Introduction Market Position Segment: Lightweight Moped / Scooter Target Audience: Enthusiasts, owners, and mechanics requiring in-depth maintenance and repair information for the Yamaha QT50. Competitive Analysis Competitors: Honda Spree, Suzuki FA50, Tomos Revival, various other 50cc two-stroke mopeds of the era. Key Features Vehicle Type: Step-through moped with automatic transmission. Manual Value Proposition: Provides essential, factory-level repair and maintenance data for preserving the longevity and performance of the Yamaha QT50. 📋 Manual Details Coverage Areas Covered Model Years: 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992 Page Count Estimated Pages: 300+ Manual Type Type: Workshop Service Manual / Repair Manual Language Language: English Format Format: PDF Download 📖 Manual Coverage Systems Covered Engine: Complete overhaul, tuning, diagnostics, carburetor, ignition system, cooling system, lubrication. Transmission: Automatic CVT (Torque Converter) system, belt replacement, clutch, gear oil. Chassis: Frame inspection, suspension (front fork, rear shock), steering system, wheel bearings. Brakes: Front drum brake, rear drum brake, brake cable adjustment and replacement, master cylinder (if applicable). Electrical: Wiring diagrams, lighting system, ignition coil, battery, charging system (stator, rectifier/regulator), switches, fuses. Fuel System: Fuel tank, fuel lines, fuel filter, carburetor (Mikuni VM series). Body And Frame: Body panels, seat, handlebars, fenders, fairings, decals, storage compartment. Procedures Included Maintenance: Routine checks, oil changes, spark plug replacement, air filter cleaning/replacement, chain adjustment (if applicable), brake adjustments, lubrication points. Repair: Engine rebuild, carburetor overhaul, transmission servicing, brake system repair, electrical component replacement, suspension overhaul. Troubleshooting: Diagnostic guides for common problems, symptom-based troubleshooting charts. Diagnostics: Engine performance issues, electrical system faults, starting problems. Technical Depth Depth: Comprehensive, covering everything from basic owner maintenance to full engine and transmission rebuilds, including detailed diagnostic procedures and specifications. 📊 Manual Specifications File Format Quality: High-resolution PDF, searchable text, clear diagrams and images. Print Quality Usability: Optimized for digital viewing and printing. Pages can be printed individually or as a complete manual. Binding Type Digital Format: N/A (Digital Download) Paper Type Digital Format: N/A (Digital Download) ⚙️ Engine Specifications Primary Engine Type: Two-stroke, single-cylinder, air-cooled Displacement: 49.2 cc Bore: 39.0 mm Stroke: 41.0 mm Compression Ratio: 7.2:1 Carburetor Model: Mikuni VM15SA Carburetor Specifications: Main Jet: #82.5, Pilot Jet: #17.5, Needle Jet: 6F52-3, Throttle Valve: #2.0, Air Screw: 1.5 Turns Out Performance Horsepower: Approx. 4.0 HP @ 6500 RPM (Varies slightly by year and market) Torque: Approx. 3.3 lb-ft @ 6000 RPM (Varies slightly by year and market) Fuel System Fuel Type: Unleaded gasoline Fuel Mixture: Pre-mix: 50:1 ratio (Gasoline to 2-stroke oil) Oil Type: Yamaha 2-stroke oil or equivalent API-TC rated oil 🔧 Transmission Standard Type: Automatic Continuously Variable Transmission (CVT) Drive Belt Part Number: 3X3-17641-00-00 Features Engagement Type: Centrifugal clutch with automatic variator. Gear Reduction: Reduction gear system for final drive. 📐 Dimensions Exterior Overall Length: Approx. 1650 mm (65 in) Overall Width: Approx. 660 mm (26 in) Overall Height: Approx. 980 mm (38.6 in) Wheelbase: Approx. 1140 mm (44.9 in) Ground Clearance: Approx. 100 mm (3.9 in) Weights Dry Weight: Approx. 65 kg (143 lbs) Wet Weight: Approx. 70 kg (154 lbs) (with fluids) Max Load Capacity: Approx. 90 kg (198 lbs) (rider and cargo) 🛡️ Safety Features Active Features Braking System: Front and rear drum brakes, operated by handlebar levers. Lighting: Headlight, taillight, brake light, turn signals (front and rear), instrument panel illumination. Passive Features Frame Construction: Steel frame providing a stable platform. Tires: Tubed tires, typically sized 2.50-10 or similar for both front and rear. 💡 Technology Features Infotainment Instrument Cluster: Analog speedometer, odometer, indicator lights for turn signals, high beam, and neutral (if applicable)....