Triumph Thunderbird Bonneville T6 Salt Flat Racer

The Triumph 6T Thunderbird was a British-built motorcycle specifically intended for the Americans, who had been asking for more power both for racing, and for sidecar applications. The Brits were the muscle bike kings in the 1940s and 1950s, and the 6T Thunderbird was built to keep that crown firmly in British hands.

Rather than build a new engine from scratch, the engineers at Triumph took the already highly regarded Triumph Speed Twin 500cc engine that had been designed by Edward Turner in 1937 and enlarged the bore. Now with a swept capacity of 650cc and well-understood internals Triumph trusted the bike enough to launch it publicly at the Autodrome de Linas-Montlhéry in France.

This autodrome had a regular race track that included a 1.58 mile banked oval that proved popular with speed and endurance testers. Triumph chose the oval for a series of speed and endurance feats for their new Thunderbird to generate publicity for the launch.

A team of factory riders rode three identical Thunderbirds, averaging a speed of 92 mph over a distance of 500 miles (over 316 laps). After this they each managed a single flying lap of over 100 mph, before riding the bikes back to the Triumph factory in England.

Source silodrome.com