🏷️ Basic Information

Make:

Yamaha

Model:

QT50 QT 50

Production Years Covered:

1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992

Vehicle Type:

Moped / Scooter

Chassis Code General:

QT50

👋 Introduction

Segment:

Lightweight, accessible urban personal transport, often favored for its simplicity and ease of use.

Target Audience:

Commuters, younger riders, or individuals seeking economical and practical transportation.

Key Competitors:

Other 50cc mopeds and scooters from manufacturers like Honda (e.g., Spree, Elite 50), Tomos, and Vespa (smaller models).

Vehicle Selling Points:

Lightweight, fuel-efficient 2-stroke engine, automatic transmission, easy handling, economical operation, and Yamaha's reputation for reliability.

📋 Manual Details

Primary Coverage:

Comprehensive Service and Repair

Specific Systems Covered:

Engine, Fuel System, Ignition System, Transmission, Chassis, Suspension, Brakes, Electrical System, Bodywork, Troubleshooting, Maintenance

Estimated Page Count:

Varies by specific edition, typically 200-300 pages

Manual Type:

Service Repair Manual

Language:

English

Format:

PDF (Digital Download)

📖 Manual Coverage

Engine:

Detailed information on the 2-stroke, single-cylinder engine, including disassembly, assembly, inspection, and repair of internal components (piston, rings, cylinder, crankshaft, bearings, seals), cylinder head, and gaskets. Includes timing, compression, and lubrication (premix).

Fuel System:

Carburetor (likely Mikuni VM series) specifications, adjustment, cleaning, and rebuilding. Fuel tank, fuel lines, and fuel filter maintenance. Fuel/oil mixing ratios.

Ignition System:

CDI ignition system details, spark plug specifications, ignition timing, coil testing, and troubleshooting.

Transmission:

Automatic centrifugal clutch and torque converter system (likely V-belt drive), including belt inspection, replacement, and adjustment. Gearbox lubrication and maintenance.

Chassis And Frame:

Frame inspection, welding repairs, and component mounting. Handlebar assembly, controls, and cable routing.

Suspension:

Front fork (telescopic) inspection, fluid replacement, seal replacement, and shock absorber maintenance. Rear suspension components, bushings, and lubrication.

Brakes:

Front and rear drum brake system maintenance, including brake shoe inspection, replacement, adjustment, and cable lubrication. Brake lever and pedal operation.

Electrical System:

Lighting system (headlight, taillight, turn signals), horn, battery maintenance, charging system (if applicable), wiring diagrams, fuse inspection, and component testing.

Bodywork And Trim:

Body panel removal and installation, seat maintenance, fenders, and decorative elements.

Maintenance Procedures:

Scheduled maintenance, oil changes (gearbox), spark plug replacement, air filter cleaning/replacement, brake adjustments, chain/belt tensioning, and general lubrication.

Troubleshooting Guides:

Systematic diagnostic procedures for common problems such as starting issues, poor performance, electrical faults, and braking problems.

Repair Procedures:

Step-by-step instructions for component removal, disassembly, cleaning, inspection, repair, reassembly, and installation.

Diagnostic Charts:

Flowcharts and charts to help identify the root cause of malfunctions.

Torque Specifications:

Accurate torque values for critical fasteners throughout the vehicle.

Depth Of Coverage:

Comprehensive, covering from basic rider maintenance to in-depth engine and transmission overhauls. Suitable for both novice DIY enthusiasts and experienced technicians.

📊 Manual Specifications

File Type:

PDF

Searchability:

Likely text-searchable, allowing for quick access to specific topics.

Resolution Quality:

Generally high-resolution scans or digital versions with clear diagrams and text.

Printability:

Designed for printing, often with page breaks and formatting suitable for home or professional printing.

Binding Type If Printed:

N/A (Digital PDF)

Paper Type If Printed:

N/A (Digital PDF)

⚙️ Engine Specifications

Engine Type:

2-stroke, single-cylinder

Cooling System:

Air-cooled

Displacement:

Approximately 49cc (exact specifications vary by regional model, typically around 49.4cc)

Bore X Stroke:

Typically 39.0mm x 41.0mm (verify in manual)

Compression Ratio:

Typically around 6.5:1 to 7.0:1 (verify in manual)

Lubrication:

Pre-mix (fuel and 2-stroke oil mixed directly in the fuel tank or via an oil injection system, though premix is more common for this era)

Horsepower Output:

Approximately 4.0 - 5.0 HP (at RPM, verify in manual)

Torque Output:

N/A (torque figures less commonly published for mopeds, focus on HP and usability)

Carburetor Model:

Likely Mikuni VM Series (e.g., VM12, VM14, or similar)

Fuel Type:

Unleaded gasoline

Recommended Oil Type:

API TC-W, API TC, or JASO FD certified 2-stroke oil (verify specific grade and viscosity in manual)

Fuel Tank Capacity:

Approximately 3.0 - 4.0 Liters (verify in manual)

🔧 Transmission

Transmission Type:

Automatic (V-belt drive with centrifugal clutch and torque converter)

Clutch Type:

Centrifugal automatic clutch

Gearbox Fluid Type:

Yamaha Gear Oil G-3, or equivalent API GL-3 SAE 80 or SAE 90 hypoid gear oil (verify in manual for specific application and capacity)

📐 Dimensions

Overall Length:

Approx. 1700mm (verify in manual)

Overall Width:

Approx. 650mm (verify in manual)

Overall Height:

Approx. 1000mm (verify in manual)

Wheelbase:

Approx. 1200mm (verify in manual)

Dry Weight:

Approx. 65-70 kg (verify in manual)

Gross Vehicle Weight Rating:

N/A (typically not specified as such for mopeds)

Maximum Load Capacity:

Typically single rider capacity, check manual for rider weight limits.

Front Tire Size:

3.00-10 4PR or similar (verify in manual)

Rear Tire Size:

3.00-10 4PR or similar (verify in manual)

Wheel Type:

Spoked or solid cast (verify in manual)

Wheel Size:

10 inch

🛡️ Safety Features

Crash Test Ratings:

N/A (Moped category generally not subject to automotive crash testing standards)

Braking System Type:

Drum brakes (front and rear)

Lighting System:

Headlight, taillight, brake light, turn signals (where applicable), reflector

Frame Construction:

Steel tube frame

Horn:

Standard

💡 Technology Features

Infotainment System:

N/A (basic instrumentation only)

Dashboard Features:

Speedometer, neutral indicator (if applicable), high beam indicator, turn signal indicators.

🔧 Maintenance

Engine Oil Change Interval:

Gearbox oil inspection and change at specified intervals (e.g., every 3,000-5,000 km or annually, verify in manual)

Spark Plug Replacement Interval:

Recommended replacement based on mileage or inspection (e.g., every 5,000-10,000 km, verify in manual)

Air Filter Cleaning Interval:

Frequent inspection and cleaning/replacement, especially in dusty conditions (e.g., every 1,000-2,000 km, verify in manual)

Brake Adjustment Interval:

Regular inspection and adjustment as needed to maintain proper braking performance.

Gearbox Oil Capacity:

Approximately 0.1 Liters (verify specific capacity in manual)

2 Stroke Oil Mixing Ratio:

Typically 50:1 or 100:1 (fuel:oil) for premix, or as per oil manufacturer's recommendation (verify in manual)

Common Wear Items:

V-belt wear, brake shoes, clutch shoes, spark plugs, piston rings, air filter, suspension seals.

Typical Failure Points:

Carburetor clogging due to infrequent use or poor fuel quality, ignition system component failure (coil, CDI), worn drivetrain components.

Importance Of Fuel Mix:

Crucial for 2-stroke engine longevity; incorrect ratio leads to lubrication failure and engine damage.

Storage Recommendations:

Proper fuel stabilization and storage procedures for extended periods out of use (detailed in manual).

📚 Vehicle History

Manufacturer:

Yamaha Motor Company

Established:

1955

Motorsport Legacy:

Strong roots in motorcycle racing and performance engineering.

Generation:

First generation (covered by this manual's production years)

Design Philosophy:

Designed for simplicity, maneuverability, and cost-effectiveness in urban environments.

Production Period:

1979 - 1992 (as indicated by the manual's coverage)

Manufacturing Location:

Likely Japan, or potentially other Yamaha assembly plants globally.

🏆 Awards & Recognition

Awards And Accolades:

N/A (as a specific model, not typically cited for awards; recognition is for Yamaha as a brand in the scooter segment).

Consumer Satisfaction:

Generally positive for ease of use and reliability when properly maintained.

Emissions Standards:

Compliant with regulations in place during its production years (details may vary by region).