Vehicle Segment:
Lightweight, entry-level scooter designed for urban commuting and recreational use.
Competitors:
Competed with similar displacement scooters from brands like Honda (e.g., Spree), Suzuki (e.g., FZ50), and Tomos.
Features:
Compact size, lightweight construction, automatic transmission, fuel efficiency, and ease of operation.
Value:
Essential for owners seeking to maintain, repair, or restore their 1990 Yamaha QT50, providing access to critical technical data and procedures.
Coverage Scope:
Comprehensive repair, maintenance, rebuilding, refurbishing, and restoration
Estimated Page Count:
Detailed manual implies a substantial page count, likely over 200 pages, covering all aspects extensively.
Type:
Full Service Repair Manual
Language:
English (presumed based on product description)
Format:
Digital (PDF) or Printed (based on typical offerings for this type of manual)
Engine:
Detailed disassembly, assembly, inspection, and adjustment of all engine components including carburetor, ignition system, cooling system (air-cooled), and exhaust system.
Transmission:
Coverage of the automatic transmission (likely V-belt type), clutch, and drive train components.
Electrical:
Wiring diagrams, troubleshooting for lighting, ignition, starting, and charging systems.
Chassis And Suspension:
Front fork, rear suspension, steering system, and frame inspection and repair.
Brakes:
Front and rear brake system maintenance, adjustment, and component replacement.
Fuel System:
Carburetor specifications, cleaning, adjustment, and fuel tank and lines.
Body And Trim:
Panel removal, installation, and cosmetic refurbishment guidance.
Maintenance:
Scheduled maintenance, lubrication, fluid changes, filter replacement, and general upkeep.
Troubleshooting:
Systematic diagnostic procedures for common and uncommon problems, including symptom-to-cause analysis.
Repair:
Step-by-step repair instructions for all major and minor mechanical and electrical components.
Rebuilding:
Detailed instructions for engine and transmission overhauls.
Recalibration:
Carburetor tuning and ignition timing adjustments.
Inspection:
Pre-ride inspections, component wear limits, and diagnostic checks.
Depth:
In-depth, ranging from basic owner maintenance to complete engine and drivetrain rebuilds, covering factory specifications and tolerances.
Digital Format:
Likely PDF with searchable text and high-resolution diagrams if digitally delivered.
Print Quality:
High-quality print with clear diagrams and legible text if printed version.
Binding Type:
Professional binding (e.g., spiral-bound or perfect-bound) for durability in workshop environments if printed version.
Paper Type:
Durable, workshop-friendly paper stock, potentially with a glossy finish for diagrams, if printed version.
Engine Type:
Two-stroke, air-cooled, single-cylinder
Bore X Stroke:
Likely around 39.0 mm x 41.4 mm (typical for this displacement).
Compression Ratio:
Typically around 7.0:1 to 7.5:1 for this era of two-stroke.
Horsepower:
Estimated 3-4 HP (highly dependent on tuning and condition).
Torque:
Low-end torque, suitable for acceleration from a stop.
Carburetor Model:
Likely a Mikuni VM series or similar (e.g., VM10/12 or a proprietary Yamaha carb).
Fuel Type:
Unleaded gasoline with two-stroke oil mixture (typically 50:1 or 100:1 depending on oil type).
Ignition Type:
CDI (Capacitor Discharge Ignition)
Cooling Method:
Forced air cooling via flywheel fan.
Overall Length:
Typically around 1700-1800 mm (subject to precise specifications in the manual).
Overall Width:
Around 650-700 mm.
Wheelbase:
Approximately 1180-1200 mm.
Dry Weight:
Approximately 65-70 kg.
Fuel Tank Capacity:
Around 3.5-4.0 liters.
Tire Size Front:
Typically 3.00-10 or similar.
Tire Size Rear:
Typically 3.00-10 or similar.
Wheel Type:
Steel wheels with pneumatic tires.
Safety Features:
Standard lighting (headlight, taillight, brake light, turn signals), mirrors, and basic safety guards.
Braking System:
Front drum brake, rear drum brake.
Lighting System:
12V system for headlights, taillight, brake light, and turn signals.
Infotainment Features:
Basic analog speedometer, odometer, and indicator lights for turn signals, high beam, and oil level (if equipped with oil injection).
Assistance Features:
No advanced driver-assistance systems. Focus is on mechanical reliability and basic operation.
Connectivity Options:
No electronic connectivity features.
Oil Change:
Gearbox oil change every 5,000-10,000 km (specific interval in manual).
Spark Plug Replacement:
Inspect and replace as needed, typically every 3,000-6,000 km depending on usage.
Air Filter Cleaning Replacement:
Clean every 1,000-2,000 km, replace as needed.
Carburetor Cleaning:
As needed, recommended every 5,000-10,000 km or if performance issues arise.
Gearbox Oil Type:
Yamaha Gear Oil (or equivalent SAE 80W-90 GL-III transmission oil).
Brake Fluid Type:
DOT 3 or DOT 4 brake fluid (if hydraulic brakes are present, though likely drum brakes requiring inspection rather than fluid).
Two Stroke Oil Type:
API TC or JASO FD certified two-stroke oil for the automatic oil injection system or for pre-mixing.
Common Problems:
Carburetor gumming/clogging due to stale fuel, worn drive belt, weak ignition coils, exhaust port blockage (carbon buildup), and worn suspension bushings are common on older two-stroke scooters.
Restoration Tips:
Thorough cleaning of the fuel system and engine are paramount for restoration. Checking for vacuum leaks and ensuring proper lubrication are critical.
Yamaha Heritage:
Yamaha Motor Company, established in 1955, is renowned for its high-quality motorcycles, scooters, and marine products, with a strong emphasis on performance and innovation.
Qt50 Lineage:
The QT50 was part of Yamaha's line of lightweight, accessible scooters, often seen as a predecessor or contemporary to models like the Jog series, focusing on urban mobility.
Production Period:
The QT50 model line was produced through the late 1980s and into the early 1990s, with the 1990 model year being a specific iteration.
