Vehicle Class:
Lightweight scooter, often referred to as a moped in its class, designed for urban commuting and recreational use.
Comparable Models:
Competed against other 50cc scooters and mopeds from manufacturers like Honda (e.g., Spree, Aero), Tomos, and various other Japanese and European brands during its production run.
Distinctive Attributes:
Compact size, fuel efficiency, ease of operation, reliable 2-stroke engine, often featured automatic transmission (CVT-like V-belt system), and distinctive styling for its era.
Supported Model Years:
1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992
Type:
Workshop Service Manual
Language:
English (Assumed based on product description)
Downloadability:
Available as an instant PDF download, providing immediate access to repair and maintenance information.
Mechanical Systems:
Engine, Fuel System, Ignition System, Exhaust System, Transmission, Drive System (V-belt), Chassis, Suspension (Front and Rear), Brakes (Front and Rear Drum), Electrical System (Lighting, Horn), Wheels and Tires.
Electrical System:
Wiring diagrams, component testing (e.g., lighting coils, regulators if present), troubleshooting electrical faults, horn, battery, and starter system (if applicable).
Maintenance And Repair:
Routine maintenance (oil changes, filter replacements, spark plug service), Engine overhaul and rebuilding, Carburetor adjustment and repair, Ignition system troubleshooting and repair, Brake system maintenance and adjustment, Suspension component inspection and replacement, Electrical component testing and repair, Clutch inspection and adjustment, Belt drive inspection and replacement, Torque specifications for key fasteners.
Troubleshooting Guides:
Diagnostic flowcharts and symptom-based troubleshooting for common issues related to starting, running, and electrical systems.
Chassis And Bodywork:
Includes procedures for frame inspection, fairing removal and installation, seat maintenance, and other body panel repairs.
Level Of Detail:
Comprehensive, covering routine maintenance, troubleshooting, and in-depth repair procedures suitable for professional mechanics and advanced DIY enthusiasts. Includes diagrams, exploded views, and step-by-step instructions.
Diagrams And Illustrations:
Features numerous exploded views, wiring diagrams, and detailed illustrations to aid in identification of parts and understanding of assembly/disassembly procedures.
Digital Format:
PDF (Portable Document Format)
Searchable Text:
PDF format may include searchable text layers, allowing users to quickly find specific topics or keywords within the document.
Printability:
High-resolution scans designed for clear viewing and printing, preserving original manual detail.
Digital Binding:
N/A (Digital PDF)
Digital Paper Simulation:
N/A (Digital PDF)
Engine Type:
Air-cooled, 2-stroke, single-cylinder
Displacement:
Approximately 49cc (specific bore/stroke details likely in manual)
Horsepower Estimate:
Typically in the range of 3-5 HP (varies with specific tuning and emissions controls)
Torque Estimate:
Low-end torque optimized for city acceleration
Top Speed Estimate:
Governed by local moped laws, typically around 45-50 km/h (28-31 mph).
Carburetor:
Likely a single Mikuni or similar brand carburetor, size dependent on specific engine variant (e.g., 14-16mm range common)
Fuel Type:
Unleaded gasoline mixed with 2-stroke oil (typically 50:1 or 100:1 ratio specified)
Ignition Type:
CDI (Capacitor Discharge Ignition) or similar electronic ignition system.
Wheelbase:
Specific dimensions available in the manual, typical for this class of scooter.
Overall Length:
Specific dimensions available in the manual, typically compact for urban maneuverability.
Dry Weight:
Likely in the 70-80 kg range (specifics in manual).
Gross Vehicle Weight Rating:
Specific GVWR detailed in manual, important for load capacity.
Crash Test Data:
N/A (Scooters of this era typically not subject to extensive crash testing as per modern car standards).
Braking System:
Front and rear drum brakes, operated by handlebar levers.
Lighting System:
Headlight, taillight, brake light, turn signals (front and rear), and instrument panel illumination.
Instrument Cluster:
Basic analog gauges, likely including speedometer, odometer, and possibly a fuel level indicator and indicator lights for turn signals and high beam. Specifics detailed in manual.
N/A:
N/A for this model and era of scooter.
N/A:
N/A for this model and era of scooter.
Oil Change Recommendation:
Periodic checks and top-ups of gearbox oil are crucial; engine oil is mixed with fuel. Specific intervals for gearbox oil changes are detailed in the manual.
Spark Plug Maintenance:
Regular inspection and cleaning/replacement, as detailed in the manual's maintenance schedule.
Belt Drive Inspection:
Crucial for performance and reliability; regular checks for wear, tension, and potential slippage are recommended (intervals in manual).
Gearbox Oil Type:
Yamaha typically specifies a specific weight of gear oil (e.g., SAE 80W or 90W), details will be in the manual.
2 Stroke Oil Mix Ratio:
Typically 50:1 or 100:1, specified by Yamaha for optimal engine lubrication and longevity. Consult manual for precise ratio.
Brake Fluid Type:
If hydraulic brakes were an option or for specific models, DOT 3 or DOT 4 brake fluid would be typical. Drum brakes may not require fluid.
Carburetor Clogging:
Common in older 2-stroke vehicles due to fuel varnish or debris. Manual provides cleaning and adjustment procedures.
V Belt Wear:
The drive belt will eventually wear and require replacement. Manual details inspection and replacement procedures.
Ignition Component Failure:
CDI units or ignition coils can fail over time. Manual provides testing procedures.
Air Filter Maintenance:
Regular cleaning or replacement of the air filter is essential for engine performance and longevity. Manual details service intervals and procedures.
Yamaha Motorcycle Division:
Yamaha Motor Corporation is renowned for its long history in motorcycle and scooter manufacturing, dating back to the mid-1950s. Known for innovation and performance across various engine sizes and styles.
Qt50 Development:
The QT50 was part of Yamaha's range of smaller displacement scooters aimed at the burgeoning commuter market, offering a stylish and economical mode of transport. Its production spanned over a decade, indicating consistent market appeal.
Manufacturing Period:
1979 - 1992
Manufacturing Location:
Likely Japan or other Yamaha international manufacturing facilities.
