Velocette KSS Mk I and II and KTT Mk I - V

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Velocette-KSS-1933-01.jpg
Velocette KSS Mk I and II and KTT Mk I - V
Manufacturer
Production KSS Mk I: 1925 - 35 KSS Mk II: 1935 - 48 KTT Mk I: 1929 - 31 KTT Mk II: 1930 - 31 KTT Mk III: 1931 - 34 KTT Mk IV: 1932 - 34 KTT Mk V 1935 - 36
Engine
Four stroke, single cylinder, OHC
Compression ratio KSS MkI & II: 7,0:1 KTT Mk I, II & III: 7.0:1 KTT Mk IV: 7.5:1 KTT Mk V: 7.75:1
Ignition Bobine
Transmission KSS: 3 Speed, hand operated KTT: 3 0r 4 Speed, foot operated
Frame KSS Mk I & II, KTT Mk I - IV: Open frame with load bearing motor to form part of the frame KSS MkV: Single cradle frame
Suspension Front: Webb fork, spring loaded adjustable dampers
Rear: Spring loaded seat
Brakes Front: 7 in. internal expanding drum
Rear: 7 in. internal expanding drum
Wheelbase 1365 mm / 53.75 in
Seat Height 711 mm / 28 in
Weight 120 kg / 265 lbs (dry),
Fuel Capacity 8.5 L / 2.25 US gal
Manuals Service Manual



Engine[edit | edit source]

The engine was a Air cooled cooled Four stroke, single cylinder, OHC. The engine featured a KSS MkI & II: 7,0:1 KTT Mk I, II & III: 7.0:1 KTT Mk IV: 7.5:1 KTT Mk V: 7.75:1 compression ratio.

Drive[edit | edit source]

Power was moderated via the Wet multi-plate.

Chassis[edit | edit source]

Stopping was achieved via 7 in. internal expanding drum in the front and a 7 in. internal expanding drum in the rear. The front suspension was a Webb fork, spring loaded adjustable dampers while the rear was equipped with a Spring loaded seat. The KSS Mk I and II and KTT Mk I - V was fitted with a 8.5 L / 2.25 US gal fuel tank. The bike weighed just 120 kg / 265 lbs. The wheelbase was 1365 mm / 53.75 in long.

Photos[edit | edit source]

Velocette KSS Mk I and II and KTT Mk I - V Velocette KSS Mk I and II and KTT Mk I - V

Overview[edit | edit source]

KSS Mk I, 1933


KSS Mk I: In 1925 the Velocette KSS (Super Sport) was released.

This was a clubmanracer, for everyone to buy, with or without lights.


The machine was designed for racing and one of the goals was to catch up on the Snaefell Mountain Course, the street circuit where the Isle of Man TT was held and at the Brooklands circuit. A top speed of 90 miles per hour (145 km/h)


On the Isle of Man, the machine had to have mainly been handling, but obviously his engine, which has a slightly higher compression ratio and received 18 to 19 hp.

External differences with other models (K and KT) were the absence of a luggage rack, a round oil tank and a round muffler. The tank was also larger and the steering slightly lower.



Alec Bennett won the 1926 Junior TT, and in 1927 Harold Willis was second and in 1928 Bennett won with Willis in second place. Willis was also a member of the board of Velocette.

It remained on the market until 1935. In 1933 the KSS received a four-speed gearbox with foot switch.

KSS Mk II: In 1935, the engine of the KSS was significantly revised.

The valves were now closed and the gearbox and frame were tweaked.

The machine used the stronger Webb fork of the new Velocette MSS.

The KSS Mk II remained in production until 1948, when it was stopped because of high production cost.


KTT Mk I: After the victories of Alec Bennett in 1928, an improved version of the KSS, the KTT (Tourist Trophy) was introduced. It had a custom clutch and gearbox.

This gearbox was the first with positive-stop foot operation.

The KTT was actually intended for competition but it was decided to sell it directly to the public.




In the production racer, the compression ratio was slightly lower than the factory racers.

In 1929 Freddie Hicks won the Junior TT with Alec Bennett in third. There were nearly 100 of these sold . Velocette had good name on the circuits in many national competitions and were very popular in the UK and Ireland.


KTT Mk II: In September 1930, the KTT MkII, appeared and was intended to be real racer.


The changes from the Mk I were only minimal. Of the Mk II only 32 complete motorcycles were built and 34 engines were sold separately.


KTT Mk III: The Mk III was released as a racer for 1932, presented in December 1931.

There boasted new cam profiles and cam followers and the engine also got a thicker (stiffer) cylinder base. The production numbers of the Mk III were limited: 32 units.


KTT Mk IV: The Mk IV came out in 1932. Now there were more changes.

There was a 14 mm spark plug and coil springs around the valves were replaced with hairpin springs. The rear frame was given an extra sub frame and Webb fork was strengthened.


KTT Mk V: In 1935, the KTT

got a new gearbox and branded "Mk V".

A new cradle frame was also fitted.

As a result, vibration was reduced and the suspension and gearbox improved.


The cylinder was to lie deeper in the crankcase and the cylinder head bolts went all the way through, so they held both the cylinder head and the cylinder.

With the Mk V, production racers were at the same level as other factory racers.

Make Model Velocette KSS Mk I, KSS Mk II, KTT Mk I, KTT Mk II, KTT Mk III, KTT Mk IV, KTT Mk V
Year KSS Mk I: 1925 - 35 KSS Mk II: 1935 - 48 KTT Mk I: 1929 - 31 KTT Mk II: 1930 - 31 KTT Mk III: 1931 - 34 KTT Mk IV: 1932 - 34 KTT Mk V 1935 - 36
Engine Type Four stroke, single cylinder, OHC
Displacement 348.4 cc / 21.3 cub in
Bore X Stroke 74 x 81 mm
Compression KSS MkI & II: 7,0:1 KTT Mk I, II & III: 7.0:1 KTT Mk IV: 7.5:1 KTT Mk V: 7.75:1
Cooling System Air cooled
Lubrication Dry sump
Carburetor Amal, twist grip (lever control optional)
Exhaust Long straight through exhaust (silencer optional)
Ignition Bobine
Starting Kick start
Max Power 14 kW / 19 hp (KTT Mk I)
Clutch Wet multi-plate
Transmission KSS: 3 Speed, hand operated KTT: 3 0r 4 Speed, foot operated
Final Drive Chain
Gear Ratios (3 Speed) 1st 9.94 / 2nd 7.6 / 3rd 5.25:1
Frame KSS Mk I & II, KTT Mk I - IV: Open frame with load bearing motor to form part of the frame KSS MkV: Single cradle frame
Wheelbase 1365 mm / 53.75 in
Seat Height 711 mm / 28 in
Ground Clearance 108 mm / 4.25 in
Front Suspension Webb fork, spring loaded adjustable dampers
Rear Suspension Spring loaded seat
Front Brakes 7 in. internal expanding drum
Rear Brakes 7 in. internal expanding drum
Fuel Capacity 8.5 L / 2.25 US gal
Dry Weight 120 kg / 265 lbs
Maximum Speed 145 km/h / 90 mph (KTT Mk I)
Colours Black with gold pin striping
Source Wikipedia