BSA 1931 S31-10 500CC 1CYL OHV 3204



BSA 1931 4.93 HP OHV de Luxe Model S 31-10 “Sloper” frame # Y10.1899. engine # Y/3742

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 (80×93 ) 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. 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. For model year 1931 the most notable is the new instrument panel that is fitted on top of the handlebars and is only available on the electrically equipped De Luxe and twin cylinder models. Model year 1932 features a less elaborate tank top mounted instrument panel so the 1931 panel is “one year only”. The panel is of the car dashboard type and includes 80 mph speedometer, amp gauge, light switch and clock. The carburettor air and ignition control levers are also accommodated within the panel. Other new features for 1931 are a hinged rear mudguard and finger adjustment to brakes. The S31-10 is the most expensive five-hundred BSA offers and we think she’s a real handsome machine. The Sloper we offer here is not perfect as to paintwork, there’s some pitting visible at places but she’s all complete and original and the chrome finish is in excellent condition. An accompanying bill shows that the engine has been rebuilt at the expense of more than 1500 Euros. This sporty BSA comes with catalogue information, bill for engine overhaul and replacement parts book.