Velocette KTT

Velocette KTT Mk I 1929

1929 VELOCETTE KTT Mk. I. In 1928 the Junior T.T. was won, as in 1926, by Alec Bennett on a Velocette, and in doing so he raised the Junior lap record to over 70 m.p.h. for the first time. Velocettes also finished second and fifth, and in October of that year the factory announced that next season they would market a replica of the winning machine, to be known as the KTT. This maker was the first to announce an over-the-counter racer and so opened the gates of road-racing with a chance of success to scores of riders, whereas, previously, only a very select few ever got factory-type racers.

The machine had a single-cylinder motor with an overhead camshaft, a very stiff crankshaft assembly and a three-speed close-ratio gearbox with positive stop footchange. The italics signify the most important point; previously racing machines had either hand-change or very occasionally kick-and-hope footchange in which selection of any gears other than top and bottom was a matter of much mischance. With its Webb strutted forks the machine steered amazingly well for its day, and in the last of the Junior Amateur T.T. races in September, 1929, the model came home in first, third, fourth, fifth and seventh places. Better was to follow, for in 1930, the first year of the Manx G.P., KTTs took the first eight places, a feat without precedent in the Island. (Just for good measure a KTT took second place in the 1929 Senior Amateur T.T.!)

It is interesting to see that, in delivery trim, on a 7-5:1 compression ratio the model was guaranteed to do 85 m.p.h. on open exhaust pipe; a piston giving 9:1 ratio was available for use with alcohol fuel, and private owners soon had them cracking at near the 100 m.p.h. All this for £80! And it only weighed 265 lb.
The factory was constantly striving to improve its racers, and it is interesting to see how they developed. The gearbox was altered to four-speed in the early thirties; hairpin valve springs were fitted and struts
were taken from the rear spindle lug to the base of the engine. It finally emerged as the Mk. VIII —

In 1926 a Velocette ridden by the Canadian champion Alec Bennet was officially entered in the 350 class of the Junior Tourist Trophy, where it achieved a stunning win. The engine of the Velocette 350 was a four-stroke single-cylinder with a bevel gear drive shaft. It generated about 25 h.p., attaining speeds up to 90 m.p.h.
Bennet showed what this racing motorcycle could do by winning second place in the 1927 edition of the Tourist Trophy and winning first place the following year, as well as setting world records. Then the Velocette company decided to produce a commercial version of its racing motorcycle. The Velocette 350 KTT was the result. Several private racers rode it to wins while waiting to be taken on by official teams.

Modeled after, the motorcycle Bennet rode, the KTT proved to be better than its predecessor. Every detail was given careful attention. The KTT had aluminum brakes and the first pedal gear in the world with its selector to the right of the engine.
Making its official racing debut in 1929, the KTT chalked up many wins and fine placings. The success of the Velocette 350 KTT was such that other major motorcycle manufacturers followed Velocette in putting their racing models into commercial production for general sale.

SPECIFICATION
Engine: single-cylinder 350 c.c. o.h.c; cast-iron head
and barrel; shaft and bevel drive to camshaft. Ignition: magneto.
Transmission: chain drive via three-speed gearbox. Frame: "diamond"-type with gearbox fixed below
to rear of engine. Forks: Webb trussed girder with single spring and
friction dampers.

Velocette KTT Mk VIII 1939

1939 VELOCETTE KTT Mk. VIII. In 1928 and 1929 the Junior I-1 T.T. was won by a Velocette of the type that was virtually the Mk. I KTT  and history repeated itself a decade later when, in the hands of Stanley Woods, "works"-entered models virtually identical to the Mk. VIII won again in 1938 and 1939. The first production batch of thirty-two Mk. VIII was described in Motor Cycling in May, 1939.

This was the first production KTT to be equipped with pivoting-fork rear suspension—a feature pioneered by this factory in the Island—and this was the main change from the Mk. VII. Light-alloy hubs were also introduced front and rear but for front suspension the T.T. Webb girder forks were retained.
The engine, dimensionally the same as the Mk. I at 74 mm. x 81 mm. stroke, had a massive alloy barrel with iron liner and a one-piece alloy head and rocker box with valve seat inserts. Compression ratio was 8-75:1 and valve control was by hairpin springs.

Although the top half of the motor was so vastly different, the crankcase was surprisingly similar to the Mk. I, showing the inherent "rightness" of the original design, with its compact yet stiffly webbed construction. For the first time, light alloy was used for the now-conical hubs themselves, with Elektron backplates.
After the war the Mk. VIII was once more produced by Velocette's and, incidentally, another decade later, won the Junior T.T. in 1947-48 and '49. In the hands of private owners the model was near invincible at small meetings, and it established a reputation for handling that few machines have ever equalled, let alone surpassed. In the early fifties, interest waned at the factory in racing and the racing shop was closed. The Mk. VIII, however, has a direct link with the current factory singles, for their four-speed gearbox is internally identical with the racer and the frame itself bears a very close family resemblance.

SPECIFICATION
Engine: single-cylinder 350 c.c. o.h.c; light-alloy head
and barrel; shaft and bevel drive to camshaft. Ignition: magneto.
Transmission: chain via four-speed gearbox.
Frame: single down-tube cradle type with pivoting-fork
rear suspension controlled by Dowty oil and air
units.
Forks: single-spring Webb girder with friction dampers-