Workshop Manual Triumph 350 & 500cc Unit Construction Twins

Triumph 350 and 500 Unit Twins 1957-1973 
Models –

Twenty-One (3TA) 348cc 1957 to 1966
T90 348cc 1962 to 1969
Speed Twin 5TA 490cc 1958 to 1966
T100 models 490cc 1959 1974

Engine – Petrol: 348 & 490cc air-cooled unit construction twin-cylinder