Category:
Lightweight Scooter / Moped
Target Audience:
Commuters, recreational riders, vintage scooter enthusiasts.
Competitors:
Honda Spree, Suzuki FA50, Tomos Revival, various other small-displacement mopeds and scooters of the era.
Design Philosophy:
Simplicity, reliability, fuel efficiency, ease of operation and maintenance, urban maneuverability.
Manual Value Proposition:
Provides essential, detailed technical information to maintain, repair, and restore the Yamaha QT50, crucial for preserving its functionality and value.
Covered Years:
1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992
Region Coverage:
Global (referencing typical Yamaha model specifications)
Estimated Page Count:
300+
Type:
Workshop Repair Service Manual
Engine:
Complete engine overhaul, diagnosis, tuning, lubrication system, cooling system, fuel system, ignition system, exhaust system.
Transmission:
Automatic transmission (CVT) disassembly, assembly, troubleshooting, fluid service, clutch operation.
Chassis:
Frame inspection and repair, front fork and suspension servicing, rear shock absorber replacement, steering system maintenance.
Brakes:
Front and rear brake system servicing, hydraulic system checks, pad replacement, drum adjustment (if applicable), bleeding procedures.
Electrical:
Wiring diagrams, lighting system, ignition system, charging system, battery maintenance, starter motor, troubleshooting electrical faults.
Bodywork:
Body panel removal and installation, seat servicing, handlebar replacement, fairing repair (if applicable), cosmetic maintenance.
Maintenance:
Scheduled maintenance tasks, oil changes, filter replacements, spark plug service, chain adjustment, tire pressure checks, brake adjustments.
Troubleshooting:
Diagnostic procedures for common starting issues, engine performance problems, electrical faults, braking system anomalies, and transmission engagement.
Repair:
Step-by-step instructions for engine component replacement, carburetor overhaul, brake system overhauls, suspension rebuilds, and electrical component repair.
Specifications:
Detailed torque specifications, fluid capacities, wear limits, electrical resistance values, and measurement tolerances.
Depth:
Comprehensive, covering routine maintenance to complete engine and component overhauls. Suitable for DIY enthusiasts and professional mechanics.
Engine Type:
2-stroke, air-cooled, reed valve induction
Bore X Stroke:
39.0mm x 41.4mm (typical for this engine family)
Compression Ratio:
7.2:1 (typical)
Carburetor Model:
Mikuni VM16-1 (typical, refer to manual for specific variations)
Horsepower:
Approximately 3.5 - 4.0 HP @ 6000 RPM (estimate, actual may vary)
Torque:
Not typically published, but designed for low-end urban acceleration.
Fuel Type:
Unleaded gasoline mixed with 2-stroke oil (50:1 ratio common, check manual for precise specification)
Fuel Tank Capacity:
Approximately 3.5 Liters (0.92 US Gallons)
Overall Length:
Approximately 1765 mm (69.5 inches)
Overall Width:
Approximately 680 mm (26.8 inches)
Overall Height:
Approximately 1055 mm (41.5 inches)
Wheelbase:
Approximately 1240 mm (48.8 inches)
Dry Weight:
Approximately 73 kg (161 lbs)
Gross Vehicle Weight Rating:
Refer to chassis plate, typically around 200 kg (440 lbs)
Crash Safety:
Not applicable in the context of automotive safety ratings. Mopeds generally lack the structural integrity and safety features of motorcycles or cars.
Braking System:
Hydraulically operated front disc brake (on some models/years), rear drum brake. Essential for safe operation.
Lighting:
Headlight, taillight, brake light, turn signals (where equipped), ensuring visibility to others.
Frame Construction:
Steel tube frame providing basic structural support.
Tyre Specification:
Front: 3.00-10 4PR, Rear: 3.00-10 4PR (typical, check manual and tires for exact size)
Engine Oil Change:
Every 1,000 km or 6 months. Refer to manual for exact specification and procedure.
Spark Plug Service:
Check at 1,000 km intervals, replace as needed based on condition.
Air Filter Cleaning:
Clean every 2,000 km or annually. Replace as needed.
Transmission Fluid Check:
Check level and condition periodically, replace as per manual's recommendation (often at major engine service).
Engine Oil Type:
Yamaha 10W-30 API SE or SF classification (verify with manual for precise specification and viscosity).
Transmission Oil Type:
Refer to manual for specific gear oil type and capacity (typically a light gear oil).
Brake Fluid Type:
DOT 3 or DOT 4 hydraulic brake fluid (check caliper/reservoir for designation).
Fuel Mixture:
Unleaded gasoline mixed with 2-stroke oil at a 50:1 ratio (crucial for engine longevity).
Carburetor Gumming:
Common with 2-strokes if left unused; requires cleaning and rebuilding. Manual provides full procedure.
Cylinder Wear:
With age and mileage, bore wear can lead to compression loss. Manual details wear limits and re-boring procedures.
Electrical Connections:
Corrosion and loose connections can cause intermittent electrical issues. Manual's wiring diagrams are essential for diagnosis.
Cvt Belt Wear:
The CVT drive belt can wear over time, affecting acceleration. Manual specifies replacement intervals and procedures.
Manufacturer:
Yamaha Motor Corporation, a global leader in musical instruments and powersports vehicles known for innovation and quality.
Design Period:
Designed for the economical and convenient personal transportation market of the late 1970s and 1980s.
Positioning:
Part of Yamaha's strategy to offer accessible and stylish mobility solutions.
Production Location:
Likely manufactured in Japan or other Yamaha global facilities during its production run.
Market Impact:
Contributed to the popularity of lightweight, fuel-efficient scooters for urban commuting and recreational use.
Market Reputation:
Considered a reliable and economical entry-level scooter during its production era.
User Reviews:
Generally positive for ease of use and low running costs, though performance is modest.
Emissions Standards:
Compliant with the emissions regulations of its respective production years. Manual may contain specific emissions control information.
