1949 650cc 6T Triumph Thunderbird
In the autumn of 1949, Triumph launched its
first post war 650cc twin with a dazzling display
of performance and reliability. Three machines,
ridden to France from the company's Meriden
factory, maintained 90mph for a distance of
500 miles on the banked Montlhery circuit near
Paris. They then completed several flying laps
at a steady 100mph before being ridden home
- all on the poor 72 octane petrol of the time.
The 6T Thunderbird was named by Triumph boss
Edward Turner, who got the idea on a business
trip to the USA. In native American lore, the
mythical eagle-like Thunderbird could unleash
thunder, lightening and rain. With its hot new
perfomer, Triumph aimed to create a storm on
the lucrative transatlantic market.
On similar lines to the successful 500cc 5T
Speed Twin introduced in 1938, the Thunderbird's
engine had larger bores, raising capacity to
650cc. It gained an extra seven horsepower,
but with the same cycle parts, the power-to-weight
ratio was much improved. Acceleration was lively
and the bigger engine cruised in a more relaxed
way, at lower revs. Like other Triumph twins
of the period, the Thunderbird was equipped
with sprung hub rear suspension and a streamlined
nacelle for the headlamp, containing a speedometer
calibrated to show rpm in the four gear ratios.
A Triumph Thunderbird famously featured in
the controversial 1953 film The Wild One, starring
Engine - 649cc (71 x 82mm) air-cooled overhead
valve paraller twin, 7:1 compression ratio,
1 1/16in Amal carburettor, magneto ignition.
Transmission - Chain primary drive, wet
multi-plate clutch, four speed gearbox, chain
Chassis - Cradle frame, telescopic fork
front suspension, sprung hub rear suspension,
Wheels - 19in.
Power - 34bhp @ 6300rpm.
Dry weight - 385lb (175kg)
Top Speed - 100mph.