Yamaha QT50 QT 50 1984 Repair Service Manual

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🏷️ Basic Information Identification Make: Yamaha Model: QT50 QT 50 Year: 1984 Vehicle Type: Moped / Scooter 👋 Introduction Market Position Vehicle Segment: Lightweight, urban-focused moped, popular for its simplicity...

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Type: Motorcycle

Vendor:

Sku: 394038

Tags: 1984 Motorcycle Motorcycles QT50 QT50 MA50 Yamaha

Product variants

Description

🏷️ Basic Information

Identification

Make:

Yamaha

Model:

QT50 QT 50

Year:

Vehicle Type:

Moped / Scooter

👋 Introduction

Market Position

Vehicle Segment:

Lightweight, urban-focused moped, popular for its simplicity and economy.

Competitive Analysis

Competitors:

Competed with other entry-level mopeds from brands like Honda (e.g., Spree, Aero), Suzuki (e.g., FA50), and Tomos.

Key Features

Design Philosophy:

Yamaha's QT50 was designed as an accessible, easy-to-operate, and fuel-efficient personal transport solution for city commuting.

Target Audience:

Young riders, commuters seeking economical transportation, and those new to motorcycling.

📋 Manual Details

Coverage Areas

Engine:

Transmission:

Fuel System:

Ignition System:

Electrical System:

Chassis:

Suspension:

Brakes:

Wheels And Tires:

Bodywork And Trim:

Maintenance:

Troubleshooting:

Wiring Diagrams:

Page Count

Estimated Pages:

Manual Type

Type:

Factory Repair Service Manual

Language

Language:

English

Format

Format:

PDF Download

File Format

File Type:

Searchability:

Searchable text content for quick information retrieval.

Printability:

Printable pages for convenient workshop use.

Print Quality

Quality:

High-resolution scans ensuring clarity of text and diagrams.

Binding Type

Binding:

N/A (Digital Download)

Paper Type

Paper:

N/A (Digital Download)

📖 Manual Coverage

Systems Covered

Engine System:

Detailed coverage of the 2-stroke engine, including disassembly, inspection, and reassembly of all components such as the cylinder, piston, crankshaft, and bearings.

Carburetion And Fuel Delivery:

Comprehensive information on the carburetor (likely a Mikuni VM series), fuel petcock, fuel lines, and air filter system, including adjustment and cleaning procedures.

Ignition System:

Detailed guidance on the CDI (Capacitor Discharge Ignition) system, including stator, ignition coil, spark plug, and timing adjustments.

Transmission And Drive System:

Coverage of the automatic centrifugal clutch, V-belt drive system, and final drive mechanism (gearbox).

Electrical System And Lighting:

Includes wiring diagrams, lighting system components (headlight, taillight, turn signals), battery charging system, and switchgear operations.

Braking System:

Detailed instructions for front and rear brake systems (likely drum brakes for this era), including adjustment, inspection, and replacement of brake shoes and cables.

Suspension And Steering:

Information on front fork assembly, rear shock absorber(s), and steering head bearing maintenance and adjustment.

Wheels And Tires:

Specifications for wheel sizes, tire types, inflation pressures, and wheel bearing maintenance.

Chassis And Frame:

Details on frame inspection, fastener torque specifications, and general chassis maintenance.

Bodywork And Cosmetics:

Guidance on removal and installation of body panels, seat, and other cosmetic components.

Procedures Included

Routine Maintenance:

Step-by-step guides for oil changes (for gearbox), air filter cleaning/replacement, spark plug checks, and brake adjustments.

Engine Overhaul:

Complete instructions for engine disassembly, cleaning, inspection for wear, and reassembly, including critical component measurements.

Carburetor Tuning:

Procedures for cleaning, rebuilding, and adjusting the carburetor for optimal performance and fuel economy.

Electrical Troubleshooting:

Systematic methods for diagnosing electrical faults using wiring diagrams, multimeter readings, and component testing.

Brake System Service:

Detailed procedures for adjusting, inspecting, and replacing brake components.

Suspension And Steering Adjustment:

Guidance on servicing and adjusting suspension linkages and steering components.

Tire And Wheel Service:

Instructions for tire pressure checks, tire replacement, and wheel bearing maintenance.

Diagnostic Charts:

Common problems and their probable causes and solutions, presented in easy-to-follow diagnostic flowcharts.

Technical Depth

Depth:

Comprehensive rebuilds and advanced diagnostics, suitable for professional technicians and experienced DIY mechanics.

⚙️ Engine Specifications

Primary Engine

Engine Type:

2-stroke, air-cooled single cylinder

Displacement:

49 cc

Bore X Stroke:

Approx. 39.5 mm x 40.8 mm (typical for 49cc 2-strokes, specific value requires manual)

Compression Ratio:

Typically around 7.0-7.5:1 (specific value requires manual)

Power Output:

Approx. 3-4 HP (specific value requires manual)

Torque Output:

Approx. 2.5-3.5 Nm (specific value requires manual)

Performance

Top Speed:

Governed by local regulations, typically around 30-35 mph.

Fuel System

Carburetor Model:

Likely Mikuni VM12 or similar (specific model number found in manual)

Fuel Type:

Unleaded gasoline with 2-stroke oil mixture (e.g., 50:1 or as specified by Yamaha)

Fuel Tank Capacity:

Approx. 3.5 Liters (specific value requires manual)

Fuel Delivery:

Gravity feed from fuel tank via petcock to carburetor.

🔧 Transmission

Standard

Transmission Type:

Automatic (CVT - Continuously Variable Transmission) with centrifugal clutch.

Features

Drive System:

V-belt drive to rear wheel via gearbox.

Clutch Type:

Automatic centrifugal clutch.

📐 Dimensions

Exterior

Overall Length:

Approx. 1750 mm (specific value requires manual)

Overall Width:

Approx. 650 mm (specific value requires manual)

Overall Height:

Approx. 1050 mm (specific value requires manual)

Wheelbase:

Approx. 1200 mm (specific value requires manual)

Weights

Dry Weight:

Approx. 70-75 kg (specific value requires manual)

Gross Vehicle Weight Rating:

Not typically specified in detail for mopeds, but rider + cargo limit implied.

Payload Capacity:

Typically 1 rider + modest cargo.

🛡️ Safety Features

Ratings

Crash Safety Ratings:

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

Active Features

Braking Type:

Front and Rear Drum Brakes.

Lighting:

Headlight, Taillight, Brake Light, Turn Signals (may vary by market).

Passive Features

Frame Construction:

Steel tube frame providing basic structural integrity.

💡 Technology Features

Infotainment

Infotainment System:

N/A (Basic transportation device, no electronic infotainment).

Driver Assistance

Driver Assistance Features:

Connectivity

Connectivity Options:

🔧 Maintenance

Service Intervals

Oil Change Gearbox:

Every 3,000 km or annually (specific interval in manual).

Air Filter Cleaning:

Every 1,000 km or as needed based on operating conditions (specific interval in manual).

Spark Plug Inspection:

Every 1,000 km (specific interval in manual).

Brake Adjustment:

Inspect and adjust every 2,000 km or as needed (specific interval in manual).

Fluid Specifications

Gearbox Oil Type:

Yamaha Gear Oil (or equivalent SAE 80W API GL-III hypoid gear oil), capacity approx. 0.7 Liters (verify in manual).

2 Stroke Oil Type:

High-quality 2-stroke engine oil, pre-mix ratio typically 50:1 (confirm in manual).

Brake Fluid:

N/A (Drum brakes typically do not use hydraulic fluid).

Known Issues

Carburetor Clogging:

Common with older 2-strokes due to fuel varnish if left sitting; requires cleaning/rebuilding.

Ignition Coil Failure:

Can be a point of failure, leading to no spark.

V-Belt Wear:

CVT belts wear over time and can slip or break, affecting acceleration and top speed.

Crankshaft Seals:

Leaking crank seals can cause vacuum leaks and poor engine running.

Exhaust Decarbonization:

2-stroke exhaust ports and mufflers can carbon up, reducing performance and causing smoky exhaust.

📚 Vehicle History

Brand Heritage

Yamaha Motors:

Yamaha Motor Corporation is a globally recognized manufacturer of motorcycles, scooters, marine products, and musical instruments, known for its engineering and performance.

Model Evolution

Qt50 Lineage:

The QT50 was part of Yamaha's lineup of lightweight, entry-level scooters and mopeds designed for accessible personal transportation during the 1980s.

Production

Production Period:

The QT50 model was produced in the early to mid-1980s.

Manufacturing Location:

Likely manufactured in Japan or potentially other Yamaha overseas facilities.

🏆 Awards & Recognition

Recognitions

Historical Accolades:

While specific awards for the QT50 are uncommon, it was recognized for its practicality and affordability in the 1980s moped market.