BSA 1931 S 31-9 493cc 1 cyl OHV 3304



BSA 1931 4.93 HP OHV de Luxe Model S 31-9 “Sloper” frame # Y72471 engine # Y101483

Presented in august 1926 for the 1927 season, the sloper sets the BSA company on the road to market domination and success. It’s brilliant designer Harold Briggs, brought in from the Daimler car company, who designs the machine around a sporty and reliable 493cc ohv (80x98mm bore x stroke) engine which inclines forward in the frame. Some typical car practice features Briggs uses in his design are sump lubrication (the crankcase is extended to form an oil reservoir holding 3 pints) and return springs within the pushrod tubes to keep the valve gear in constant touch with the cam profiles, giving exceptionally quiet operation. For model year 1929 a side valve version is introduced with the same bore x stroke dimensions. The Sloper soon gets a reputation as a sporting but quiet motorcycle, a real trendsetter. A new feature for the 1930 model year is the forged steel backbone of which the company claims: “A backbone of forged steel- that’s one of the outstanding features of these new B.S.A. O.H.V. models. Motor cyclists will recognise the significance of this unique feature in motor cycle construction, which means super-strength in one of the most vital parts of the motor cycle – the frame. It means rigidity – absolute stability on the roughest roads – and greater safety.” BSA makes sure that every year some improvements can be announced. Some new features for 1931 are a hinged rear mudguard and finger adjustment to brakes.

This handsome all-black Sloper was first registered on March 11, 1931. She has a current French registration and is a smooth runner. With the machine come overhaul and maintenance bills to the amount of more than 1500 Euros. Accessories include 85 mph Smiths speedo and rear view mirror.