Launched in 1957 as the Model 3TA, then called the "Twenty one", was the first of the Triumph unit construction twin cylinder motorcycles.
With a capacity of 349 cc, the engine is a classic Edward Turner design with a twin gear driven camshafts, a 360 degree crankshaft and twin plunger oil pump.
The cylinder block is cast iron with an alloy head and separate rocker boxes.
The engine has dry sump lubrication and there is a single carburettor.
Drive is by a conventional four speed gearbox, with a right hand gear lever.
The Triumph 3TA was also produced as a 500 cc version, the Triumph 5TA, which is also referred to as the 'new Speed Twin'.
The 'A' designation is a reference to the fact that both motorcycles are fitted with an alternator as standard, as the pre-unit models had been fitted with a dynamo.
The first versions of both the 350 cc and 500 cc models have the fully enclosed rear end which was fashionable in the late 1950s.
The 3TA continued in production until 1967 when it was succeeded by the T90.
3TA`s were also widely used in militairy service for some time.
This near complete Triumph 3TA is a challenging, straightforward project with a good value potential.