BSA 1931 S31/10 500cc 1 cyl ohv



BSA   1931  4.93 HP   OHV   S 31 – 10  “Sloper”   frame# Y7284 engine# Y101549

Presented in august 1926 for the 1927 season, the sloper  set the BSA company on the road to market domination and success. 
It was brilliant designer Harold Briggs, brought in from the Daimler car company, who designed the machine around a sporty and reliable 493 cc ohv (80×98 ) engine which inclined forward in the frame. 
Some typical car practice features Briggs used in his design were sump lubrication ( the crankcase was 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 got a reputation as  a sporting but quiet motorcycle, a real trendsetter. 
Apart from the OHV model two side valve slopers were marketed,  a 493 cc model and a 557cc model. 
In 1930 the model got a forged “backbone” upper frame to increase stability and riding position. 
This model  has got the luxury of a dashboard with  speedometer, ampere gauge, light switch and steering damper.