The Yamaha QT50 Yamahopper is a small moped that Yamaha produced from 1979 to 1992. It was easy to ride and maintain, very economical and unusual for using a shaft drive instead of a chain.
Yamaha QT50 at a glance
| Maker | Yamaha Motor Company |
|---|---|
| Class | Moped |
| Production | 1979–1992 |
| Engine | 49 cc two-stroke single |
| Bore and stroke | 40 × 39.2 mm |
| Compression | 6:1 |
| Carburettor | Mikuni VM12SC with reed valve |
| Fuel economy | about 135 mpg |
| Top speed | about 30 mph |
| Drive | shaft in a single-sided swingarm |
| Transmission | centrifugal clutch, single speed |
| Maximum load | about 186 lb |
Based on one source (English Wikipedia).
History of the Yamaha QT50
The QT50 was built from 1979 to 1992 as an easy, economical moped. Its 49 cc two-stroke single was almost square, with a 40 mm bore and 39.2 mm stroke, and a compression ratio of 6:1. Fuel came through a Mikuni VM12SC carburettor and a reed valve, and Yamaha’s Autolube system metered the oil so the rider did not have to mix it. Because the engine was under 50 cc, the QT50 could be ridden without a motorcycle licence in some American states.
The moped had turn signals, solid-state CD ignition, front and rear luggage carriers and drum brakes at both ends. Its top speed was about 30 mph and its maximum load around 186 lb, which made it suitable for city use. The QT50 looked like a moped of its time but shared some features with scooters, and it resembled the Honda Express, although it had no fairing, used footpegs rather than footboards and hung its engine beneath a monotube frame in motorcycle style.
Its most distinctive feature was the drivetrain. The compact, weatherproof shaft drive ran in a single-sided swingarm, eliminating chain maintenance and making wheel changes easy, an arrangement with similarities to some BMW shaft systems. A traditional centrifugal clutch was used with single-speed gearing. Many parts are interchangeable with the engines of the YF60 quad, YT60 ATV, MJ50 and PW50, all derived from the QT50 unit, and most parts were still available from Yamaha dealers long after production ended.
Design and features
- Shaft drive: a maintenance-free drive in a single-sided swingarm, unusual for a moped.
- Autolube: automatic oil metering removed the need for premixed fuel.
- Practical equipment: turn signals, CD ignition and front and rear luggage carriers.
- Shared engine family: the YF60, YT60, MJ50 and PW50 used derived engines with interchangeable parts.
Yamaha QT50 versions
- QT50 Yamahopper (1979–1992): the only production version.
- Derived models: YF60, YT60, MJ50 and PW50 used related engines.
The QT50 is related to the PW50 through its engine family. More models are in the Yamaha collection.
Sources
- Yamaha QT50, English Wikipedia: production, engine, economy, shaft drive, shared parts
.jpg){kind=link}