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Triumph Thunderbird

Triumph Thunderbird
Triumph 6T 650 cc Thunderbird 1950.jpg
1950 Triumph 6T Thunderbird
Manufacturer Triumph Engineering Co Ltd
Also called 6T, TR65
Production 1949–1966
Predecessor Speed Twin
Engine Four-stroke Parallel-twin
Power 34 bhp (25 kW) at 6300 rpm
Transmission Four speed
Wheelbase 55 in (1,397 mm)
Dimensions W: 27.5 in (698 mm)
Seat height 31.5 in (800 mm)
Weight 385 lb (175 kg) (dry)
397 lb (180 kg) (wet)
Related Tiger T110

The Triumph Thunderbird is a British motorcycle that was introduced by Triumph in 1949 and produced in many forms until 1966. The name was used three more times for new and distinct Triumph models.

To capture the American market, the 6T Thunderbird used a variant of the earlier Speed Twin's parallel twin engine, bored out from 500 cc to 650 cc to give the added horsepower American customers demanded. The concept of enlarging the Speed Twin, the Thunderbird name and its 'paper dart' logo were thought up by managing director Edward Turner on one of his regular trips to Triumph's operations in the USA. The 'paper dart' logo was embossed onto the chain case cover on Thunderbirds from 1955 to 1962 and can be seen upon closer examination on the supplied photograph of the 1962 model. Previously, it appeared as a decal on the headlamp nacelle.

The 6T Thunderbird was launched publicly at Montlhéry near Paris, where three standard-production bikes were ridden around a circuit by a team of riders who between them averaged a speed of 92 mph (148 km/h) over a distance of 500 miles (800 km). All three machines were ridden to the circuit and back to the Meriden factory.

Triumph obtained further lasting publicity with Marlon Brando's 1953 motion picture The Wild One, in which he rode a 1950 6T Thunderbird. In the book Triumph Motorcycles In America, there is reproduced a letter from Triumph's importers objecting to the producers as to the use of their machine in this film about rowdy motorcycle gangs.

From 1960, the Thunderbird acquired Turner's rear fairing nicknamed the 'bathtub' on account of its shape. This unpopular feature, dropped quickly in the USA market, remained in ever-abbreviated forms for the home market until disappearing altogether for the final year of production, 1966. Before then, in 1963, the Thunderbird, along with Triumph's other 650 cc models, was given the Turner-designed unit engine. Throughout this time, however, the Thunderbird retained its distinctive nacelle. A 1966 Thunderbird was prominently used by the leads in the popular 2006 romance film, Once.

The Triumph worker's co-operative at the Meriden factory re-introduced the Thunderbird model name to their range in April 1981. The Triumph TR65 Thunderbird 650 cc parallel-twin was a short-stroke version of the 750 cc T140 Bonneville engine and was the cheapest model in Triumph's range with budget features such as a drum rather than disc rear brake, the absence of a tachometer, a siamesed exhaust system, painted rather than polished alloy and economy Dunlop Gold Seal tyres. Moreover, whereas Triumph's 750cc range had electronic ignition, the TR65 was fitted with contact breaker points. Respecting its lineage, the model retained the Turner-designed 'paper dart' logo on its side panels but with a different, updated 'Thunderbird' script. The TR65 was priced upon introduction at £1829.82. The economy finish was upgraded for 1982 'export' models although the contact breaker points and drum rear brake remained.


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