Lot details
Registration No: NKT 138
Frame No: S7-5266
Engine No: S87466
cc: 500
MOT Expiry Date: None

The Sunbeam concern had been acquired by BSA during 1943 and a new machine bearing the Sunbeam name was described to the press in early 1946. It was intended as the "group flagship" and consequently, Erling Poppe designed a machine that incorporated many innovative features. The short-stroke, overhead cam, in line twin cylinder engine was mated to a shaft final drive via a four speed gearbox with an under slung "worm" gear transmitting the drive to the rear wheel. The all alloy engine and gearbox were mounted in a duplex frame equipped with plunger rear suspension, telescopic forks, 16 inch balloon tyres and sprung saddle. However, harsh running, a peaky power delivery and rapid wear of the worm gear were identified during pre production testing which resulted in the models release being delayed until 1947 whilst solutions were sought. The BSA design staff opted to detune the engine which rectified the worm gear wear and to rubber mount the engine and gearbox which addressed the harshness issue. The S& was joined in 1949 by a more sporting variant typed the S8. The S8 reverted to normal section tyres and employed standard BSA forks and front brake. The two machines continued to be offered until 1957, selling steadily to their target market of discerning enthusiasts a, trend that continues today.
This example is finished in the distinctive mist green livery synonymous with the model and has been restored to a very high standard cosmetically prior to entering the private collection.