Velocette KTT
Velocette KTT Background & History
The 350cc Velocette KTT was in production from 1929 through the 1949 model year, with a interruption on civilian production during World War 2 from 1940 through 1945. The KTT was part of Velocette’s K series of overhead cam singles. The “K” in the name signifies overhead cam (OHC) and the “TT” means it was intended for road racing, although many were equipped for legal road use. This is an early example of what would later be referred to as a ‘factory production racer’. The KTT was the first production motorcycle to feature a positive-stop foot-operated gear change, and the first with a swing arm rear suspension with two shock absorbers (what would be considered conventional today). This separates it from it’s K series stablemate the KSS (the “SS” stands for Super Sport) which only had a rigid frame throughout its entire production life (1925-48).
This 1929 Velocette KTT was the Mark I, meaning the first year of production. Note the rigid frame and girder front forks.
Velocette KTT Wins Races
Based on the KSS, the Velocette KTT was designed specifically to compete as a production race in the Isle of Man TT which was the most important motorcycle race at the time. The sons of Velocette founder Johannes Gutgemann, Percy and Eugene Goodman (the Americanized their German name) built a racing version of the KSS and in a matter of months secured their first TT win in 1926. Three KTTs finished in the top 9 which secured the team prize for the factory. The KTT went on to become one of the most successful 350cc production racers of all time with a host of international wins.
This 350cc 1929 Velocette KTT engine shows the vertical tube that houses the shaft that drives the overhead cam. Note the exposed 'hairpin'-type valve springs.
Velocette KTT Constantly Improving
The development of the Velocette KTT was relentless, proving that racing does indeed improve the breed. At a time when most motorcycles, including racers, were still hand shifted. Velocette perfected foot shifting, which helped them win races and it trickled down to their street bikes. Development stages were organized by ‘Marks’ with the Veclocette KTT’s first year of 1929 designated as Mark I, and each successive year was another Mark. The first significant change came in 1935 with the Mark V KTT when the old open-bottom frame that used the engine as a stressed member was dropped in favor of a full cradle frame. This was the same rigid frame that the KSS was using. 1936 saw a break in Velocette KTT production as only 6 Mark VI KTTs were built, and only for special clients. The Mark VI was also the first KTT to use an aluminum cylinder head, borrowed from the KSS.
This 1949 Velocette KSS represents the final year of production. It shows the benefits of a swing arm frame with air shocks, and the heavily finned engine.
Big Changes for the Velocette KTT
Around this time, Velocette hired Stanley Woods to ride for the Veloce Racing Team and he feedback led to changes in the KTT. For 1937, the Mark VII KTT saw the ending moved forward roughly 1-1/2 inches to improve handling, and a new aluminum top end (cylinder and head) with heavy finning for added cooling. The new setup made more power, but alas only 37 Mark VIIs were built. Talking about racing improving the breed, a revolutionary new swing arm rear suspension with two shock absorbers was introduced first on the factory race team bikes, then by 1938 it showed up on production Mark VIII Velocette KTTs. One of Veloce’s designers, Harold Willis, was a private pilot and so he was familiar with Oleo suspension legs used on light planes. He contracted Oleo to make the air shocks used on the Velocette KTT.
This 1949 Velocette KTT engine shows the heavy finning on the aluminum cylinder and head, and all the top end oiling lines.
Velocette Never Made a Twin
When Velocette KTT production ended in 1949, they’d built 238 KTTs in that model year, probably it’s best year ever. Because over it’s 32-year production life, less than 1,000 KTTs were built. Velocette built some of the finest single cylinder motorcycles in the 1930s when singles ruled the earth. However, they’d been eclipsed in the late 1940s by the vertical twin. When Triumph launched is game-changing 500cc vertical twin in the 1938 5T Speed Twin the rest of the industry, those who could afford it anyway, to rush to get a vertical twin of their own. The was delayed things, but when civilian production resumed in 1946 the race was on. BSA, Ariel, Royal Enfield, Norton and Matchless/AJS all 500cc vertical twins in jus 4 years. Velocette couldn’t afford to develop a twin, and at the time they may not have thought they needed to. The leadership at Velocette probably thought their singles were so good (and they were) that they’d be okay. Actually most of Triumph’s competitors never sold enough twins to justify the investment. Royal Enfield, Ariel and Matchless/AJS never reached their breakeven point on their twins. So, maybe Velocette didn’t miss the boat after all.
1949 Velocette KTT engine, final year of production, primary side.
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