Triumph Twenty One

The Triumph Twenty One, also known as the 3TA, is a standard motorcycle made by Triumph Engineering Co Ltd in Coventry. Launched in 1957, it was the first of the Triumph unit construction twin-cylinder motorcycles from the Meriden factory. It was rebranded the 3TA in 1959 and stayed in production until 1966, after which the T90 sports version continued. Its 349 cc engine was a classic Edward Turner design with a 360 degree crankshaft, twin gear-driven camshafts and a twin plunger oil pump, a cast iron block with an alloy head and separate rocker boxes, dry sump lubrication and a single Amal Monobloc carburettor, driving through a four-speed gearbox with a right foot gear lever.