Yamaha QT50 QT 50 1979-1992 Full Service Repair Manual

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The QT50, also known as the QT 50 scooter, was produced from 1979 through 1992. This lightweight and user-friendly scooter was designed for urban commuting and younger riders, offering ease...

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类型: Motorcycle

斯库: 57654

标签: 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 Motorcycle Motorcycles QT 50 QT50 QT50 MA50 Yamaha

产品多属性

Description

The QT50, also known as the QT 50 scooter, was produced from 1979 through 1992. This lightweight and user-friendly scooter was designed for urban commuting and younger riders, offering ease of operation and fuel efficiency. Key features include an automatic continuously variable transmission (CVT), a compact 49cc two-stroke engine providing brisk acceleration for its class, and often electric start functionality. The reputation for engineering quality and reliability is a hallmark of the QT50, making it a popular choice in its segment, competing with other small-displacement scooters of the era. This comprehensive service repair manual provides detailed information for the maintenance, diagnosis, and repair of the QT50 scooter across its production years. It covers all major systems, including the engine, fuel system, ignition, transmission, brakes, suspension, and electrical components. The manual includes scheduled maintenance tasks, troubleshooting guides for common issues, step-by-step repair procedures, and technical specifications. This resource is essential for owners, mechanics, and technicians to ensure the proper upkeep and longevity of the QT50, facilitating everything from basic adjustments to major overhauls.

🏷️ Basic Information

Identification

Make:

Yamaha

Model:

Model Nickname:

QT 50

Vehicle Type:

Scooter

Product Type:

Full Service Repair Manual

Codes

Chassis Code General:

👋 Introduction

Market Position

Positioning:

The Yamaha QT50 was a popular, lightweight, and user-friendly scooter in its era, often marketed towards younger riders or for urban commuting due to its ease of operation and fuel efficiency.

Competitive Analysis

Competitors:

Competed with other small-displacement scooters from manufacturers like Honda (e.g., Spree, Aero) and Suzuki (e.g., Streetmag). Its key differentiators were Yamaha's reputation for reliability and often distinctive styling.

Key Features

Features:

Automatic transmission, lightweight design, electric start (often), and a compact 2-stroke engine providing peppy acceleration for its class.

📋 Manual Details

Coverage Areas

Years Covered:

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

Geographical Coverage:

Likely global, with specific regional variations noted if applicable to repair procedures.

Page Count

Estimated Page Count:

Varies by specific edition, typically 200-400 pages for comprehensive manuals of this era.

Manual Type

Type:

Service Repair Manual

Language

Language:

English

Format

Format:

PDF Download

📖 Manual Coverage

Systems Covered

Engine:

Complete engine disassembly, assembly, tuning, troubleshooting, and overhaul procedures for the 2-stroke engine.

Fuel System:

Carburetor (Mikuni VM series likely) adjustment, cleaning, and overhaul; fuel tank, petcock, and fuel lines.

Ignition System:

CDI ignition system, spark plug diagnosis, coil testing, stator inspection.

Transmission:

Automatic transmission (CVT - Continuously Variable Transmission) inspection, belt replacement, clutch adjustment, and gearbox lubrication.

Brakes:

Front and rear drum brake systems, brake lever and cable adjustment, brake shoe replacement, and drum inspection.

Suspension:

Front telescopic forks (servicing, oil change, seal replacement) and rear shock absorber unit (inspection, replacement).

Electrical System:

Wiring diagrams, lighting (headlight, taillight, turn signals), horn, battery maintenance, fuse inspection, and basic electrical troubleshooting.

Cooling System:

Air-cooled engine design - focus on cylinder head and barrel fins for heat dissipation.

Chassis And Body:

Frame inspection, body panel removal and installation, seat, handlebars, and fairing components.

Procedures Included

Maintenance:

Scheduled maintenance tasks, lubrication points, filter replacement, spark plug checks, and general upkeep.

Troubleshooting:

Diagnostic charts and procedures for common running issues, starting problems, and performance degradation.

Repair:

Detailed step-by-step instructions for component repair and replacement across all systems.

Rebuilds:

Engine and carburetor rebuild procedures with specifications and tolerances.

Adjustments:

Carburetor idle speed and mixture, brake lever free play, throttle cable slack.

Technical Depth

Depth:

Comprehensive, covering basic maintenance to major overhaul and component-level repair.

Diagnostic Capability:

Includes diagnostic procedures and specifications for identifying and rectifying faults.

📊 Manual Specifications

File Format

Format:

PDF (Portable Document Format)

Searchability:

Likely text-searchable PDF, allowing for quick navigation and keyword finding.

Print Quality

Quality:

Digital, quality is dependent on the source scan/creation but generally good for clarity of text and diagrams.

Binding Type

Type:

N/A (Digital format)

Paper Type

Type:

N/A (Digital format)

⚙️ Engine Specifications

Primary Engine

Engine Type:

2-stroke, air-cooled, single-cylinder

Displacement:

Approximately 49cc (specific figures may vary slightly by market variant).

Bore X Stroke:

Typical for this class: ~39.0mm x 41.4mm (check specific manual for exact figures).

Compression Ratio:

Likely around 7.0:1 to 7.5:1 (check specific manual).

Lubrication:

Pre-mix or Autolube system (automatic oil injection).

Performance

Horsepower:

Typically in the range of 4-6 HP at specific RPM (check manual for exact rating).

Torque:

Torque figures would be modest, optimized for low-end acceleration.

Fuel System

Carburetor Model:

Likely Mikuni VM Series (e.g., VM16SC or similar).

Fuel Type:

Unleaded gasoline

Fuel Octane Rating:

87 AKI (Anti-Knock Index) or higher.

Oil Type Autolube:

Yamaha recommended 2-stroke oil or equivalent API TC/JASO FD certified oil.

🔧 Transmission

Standard

Type:

Automatic Continuously Variable Transmission (CVT)

Drive Type:

Belt drive from CVT to rear wheel.

Optional

Optional Types:

Features

Clutch Type:

Centrifugal automatic clutch

Gear Ratios:

Continuously variable via V-belt and pulleys. Specific pulley ratios and belt specifications available in manual.

Transmission Fluid:

Gear oil for the final drive. Specific viscosity and capacity detailed in the manual (likely SAE 80 or 90).

📐 Dimensions

Exterior

Overall Length:

Approx. 1660 mm (check manual for exact spec).

Overall Width:

Approx. 670 mm (check manual for exact spec).

Overall Height:

Approx. 1010 mm (check manual for exact spec).

Weights

Dry Weight:

Approx. 65-70 kg (check manual for exact spec).

Curb Weight:

Likely slightly higher than dry weight due to fluids.

Weight Distribution:

Designed for stability at low speeds, typically balanced.

Cargo

Storage:

Under-seat storage compartment, rear luggage rack provisions.

🛡️ Safety Features

Ratings

Crash Test Ratings:

N/A (Scooters of this era were not typically subjected to standardized crash testing like modern automobiles).

Active Features

Braking System:

Front and rear drum brakes for controlled stopping.

Lighting:

Headlight, taillight, brake light, and turn signals for visibility.

Passive Features

Frame Construction:

Steel frame designed for rigidity and rider support.

Handlebars:

Provide rider control and leverage.

💡 Technology Features

Infotainment

Features:

Basic analog speedometer, odometer, and indicator lights (turn signals, neutral, oil indicator if applicable).

Driver Assistance

Features:

None typically found in scooters of this era.

Connectivity

Features:

🔧 Maintenance

Service Intervals

Oil Change Final Drive:

Typically every 3,000-5,000 km or annually (refer to manual for precise interval).

Spark Plug Check:

Every 1,000-2,000 km or as needed for performance issues.

Air Filter Cleaning:

Every 1,000-2,000 km, depending on operating conditions.

Carburetor Cleaning:

As needed for performance issues, or proactively every 5,000-10,000 km.

Brake Adjustment:

Regularly check for proper lever free play.

Cvt Belt Inspection:

Inspect for wear and damage every 3,000-5,000 km, replace as necessary.

Fluid Specifications

Transmission Oil Viscosity:

SAE 80 or SAE 90 Gear Oil (verify with manual).

2 Stroke Oil Type:

Yamaha Super 2-Stroke Oil, API TC, JASO FD (or equivalent).

Known Issues

Common Problems:

Carburetor gumming/clogging due to infrequent use or poor fuel quality, CVT belt wear, weak ignition spark due to CDI or coil failure, exhaust port restrictions from carbon buildup in the 2-stroke engine.

Preventative Maintenance:

Regular use to keep components clean and lubricated, using fresh fuel, and adhering to service intervals.

📚 Vehicle History

Brand Heritage

Heritage:

Yamaha Motor Corporation has a long history of producing high-quality motorcycles and scooters, known for innovation and performance.

Model Evolution

Evolution:

The QT50, introduced in the late 1970s, represented Yamaha's offering in the burgeoning 50cc scooter market, characterized by its simplicity and affordability.

Production

Production Period:

1979 to 1992

Manufacturing Location:

Likely manufactured in Japan or other Yamaha overseas facilities.

🏆 Awards & Recognition

Recognitions

Awards:

No specific awards widely documented for this model, but recognized as a reliable and popular entry-level scooter.