Without doubt one of the great British sporting motorcycles, the Velocette KTT (Kamshaft Tourist Trophy) enjoyed an illustrious career spanning three decades. The KTT series first become available as a road machine at the end of 1928 when two MK I’s were built. Production of the successful new model accelerated in 1929 when 178 were produced.
MK I–MK IV, 1928–34
As the name implies, the appeal of the KTT was that it was a very successful production racer offered to the public in a road going version. The KTT model series all benefited from the experience gained by the successful Velocette works team, the MKI being in effect a replica of the works machines that had secured Velocette’s second TT win in the 1928 Junior race. The new model was powered by an overhead cam single cylinder engine displacing 348cc with a bore and stroke of 74 x 81 mm that could be distinguished from the road going models in the range by the external stiffening webs employed on the crankcase. Lighter, steel flywheels were employed and a hotter camshaft was fitted.
The works paid a great deal of attention to strengthening the valve train to prevent breakages and a revised cylinder head was fitted. Drive was taken to a three speed gearbox, similar to that used by the rest of the Velocette range but fitted with a set of close ratio gears, via a primary chain.
The well balanced rigid frame was equipped with a set of braced Webb girder forks, a design feature peculiar to the KTT. The MkII model ran in this form with only detail alterations until 1932 when the MK IV was introduced.
The Mk IV was fitted as standard with the new positive stop four speed gearbox which had previously been available as an option and a new cylinder head, still cast in iron, was employed, which offered improved combustion characteristics.
MK V–VII, 1935–37
1935 saw the introduction of the MK V which brought in a totally revised chassis employing a full cradle frame and a redesigned engine. The MK V remained in production until 1936.
No KTT model was listed officially in 1937, but 1938 witnessed the introduction of a new KTT, the MK VII. The new version had a massively finned alloy head and barrel and new front, girder type forks.
MK VIII, 1938—50
The MK VII remained in the catalogue for a season before being replaced by the definitive 1938 KTT MK VIII. The MK VIII, which would, with a break for the Second World War, remain in production until 1950, introduced a completely revised frame with a rear swing arm controlled by pneumatic/hydraulic rear damper units. With its deep profile black and gold petrol tank, heavily finned overhead-cam engine, sweeping exhaust and purposeful stance, the Velocette MkVIII KTT is unquestionably one of the most beautiful racing motorcycles ever made. The talking point of Velocette’s new KTT racer on its introduction at the 1938 Earls Court Show was the innovative swinging-arm rear suspension, first seen on their works bikes in 1936. By now tried and tested, the Velocette rear suspension comprised a pivoting fork made from tapered tubing and
complemented by a pair of Dowty Oleomatic air-sprung struts. The rest of the KTT parts remained much as those of the rigid-framed MkVII. The engine, while basically the same as its predecessor’s, incorporated a number of improvements intended to enhance power and reliability, and despite the springer’s increase in weight over the rigid model, its superior performance and excellent handling made the MkVIII KTT a formidable competitor. Indeed, the production version differed little from the works bikes that had dominated the 1938 Isle of Man Junior TT, when Stan Woods lead home team-mate Ted Mellors to break Norton’s seven-year stranglehold on the event. A win which Woods repeated the following year.
Despite its pre-war origins, the MkVIII KTT proved good enough to provide Freddie Frith and Velocette with the 350cc World Championship in 1949. Frith won every round, though in most cases courtesy of a special works twin-cam engine, while in 1950 Bob Foster won three out of six to bring the 350cc World Championship back to Velocette’s Hall Green factory for the second successive year. Production of the customer KTT ended in 1950, only 49 MkVIIIs had been constructed before the war and a further 189 after. Numbers of the Works engine are not fully known, but it is thought that only 6 units were completed in the post war period up to 1950. Velocette stopped developing machines for GP racing soon after this and their race success in the future came with modified road bikes, this was due mainly to the very high cost of competition racing at the highest level. Today the MkVIII KTT is one of the most desirable of all pre war British racers.