Triumph Twenty One

The Model Twenty One was the first of the Triumph unit construction twin cylinder motorcycles.

[1] Launched in 1957 the Model Twenty One was the first of the Triumph unit construction twin cylinder motorcycles from the Meriden factory.

The cylinder block was cast iron with an alloy head and separate rocker boxes.

The engine was dry sump lubrication and there was a single Amal Monobloc carburettor.

They also found that the extra sheet metal made access for servicing more complicated.

Triumph 'Twenty One' with the abbreviated 'bikini' version of the 'bathtub' rear fairing
One of the last versions: a 1966 Dutch Army Triumph 3TA 'Twenty One', now on display at the Marshallmuseum, Overloon.
1965 350cc Triumph T90 Tiger. Built from 1962 to 1968, this was the sports version of the Triumph Twenty One
After a single season, the 1964 350cc Triumph T90 Tiger dispensed with the unpopular 'semi-bathtub' or 'bikini' rear fairing still to be found upon the 3TA.