Velocette KTT: history, specs, pictures

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Velocette KTT

Velocette's enormously successful KTT series had been developed for 14 years when the Mk VIII appeared at the Earls Court Show in 1938. Priced at £120, the model was another 'race replica' in the great Velocette tradition and included a host of innovations seen on the works machines that had won that year's Junior TT.

With lightweight alloy parts, sophisticated oiling and a pioneering suspension design, it showed all the benefits of development by a consistent programme of racing. The most notable feature of the engine was its massive cylinder head casting, with its squared-off light alloy fins virtually filling the frame. Introduced on works racers in 1937 and sold to the public as a limited run of Mk VII KTT's early in 1938. Similar finning extended to the rocker box, which contained a labyrinth of oil ways to lubricate the bevel gears and cams.

The Mk VII had a fairly modest state of tune (with an 8.75:1 compression ratio) and a rigid frame with few special fittings. The Mk VIII was altogether a different proposition. It featured swinging-arm rear suspension and Dowty oleo pneumatic rear shock absorbers, in which the springing was by air under pressure, with oil damping. It had lightweight magnesium alloy brake hubs and a telescopic housing for the front fork spring, while the engine had been beefed-up to an 11:1 compression ratio. The valves on the works bikes were filled with sodium for better cooling.

Ridden by Stanley Woods, the Mk VIII won the 1939 Junior TT for the second year running, just after the Velocette's great designer Harold Willis had died of meningitis. The model did well in private hands too, lapping the Brooklands circuit at 100mph.

War then brought a close to racing as to so many other things and Velocette built around 2200 versions of its pushrod models for military use. When production resumed after the war, the Mk VIII was good enough to take two 350cc world championships and win the Junior TT three years running. Production continued until 1950, by which time the double overhead-cam Manx Nortons were taking the honors in world class racing. But with a top speed of 105mph, the production career with enthusiastic amateurs, who celebrated the brilliance of a design that enjoyed almost a quarter of a century at the top.

Velocette KTT Stats[edit | edit source]

  • Years in production*1938-50
  • Engine*single cylinder overhead-cam four-stroke
  • Bore and Stroke*74 x 81mm
  • Capacity*348cc
  • Compression ratio*10.9:1
  • Top speed*110mph
Velocette KTT
Also called KTT Mk VIII
Production 1938 - 1950
Class Road
single cylinder, four-stroke
Bore / Stroke 74.0mm x 81.0mm
Top Speed 115 mph (185 km/h)
Horsepower 34.2 HP (25.5 KW) @ 5800RPM
Fuel System carburetor
Ignition bobine
Transmission Final Drive: chain
Clutch: wet multiplate
Suspension Front: webb girder forks
Rear: swingarm
Brakes Front: expanding brake (drum brake)
Rear: expanding brake (drum brake)
Weight 275.58 pounds (125.0 Kg) (dry),
Fuel Capacity 4.0 Gallon (15.14 Liters)
Manuals Service Manual

The Velocette KTT Mk VIII was a single cylinder, four-stroke Road motorcycle produced by Velocette between 1938 and 1950. It could reach a top speed of 115 mph (185 km/h). Claimed horsepower was 34.2 HP (25.5 KW) @ 5800 RPM.

Engine[edit | edit source]

The engine was a air cooled single cylinder, four-stroke. A 74.0mm bore x 81.0mm stroke result in a displacement of just 348.4 cubic centimeters. Fuel was supplied via a overhead valves (ohv).

Drive[edit | edit source]

Power was moderated via the wet multiplate.

Chassis[edit | edit source]

Stopping was achieved via expanding brake (drum brake) in the front and a expanding brake (drum brake) in the rear. The front suspension was a webb girder forks while the rear was equipped with a swingarm. The KTT Mk VIII was fitted with a 4.0 Gallon (15.14 Liters) fuel tank. The bike weighed just 275.58 pounds (125.0 Kg).

In Media[edit | edit source]