The BSA S series was produced from 1927 to 1935. The 493 cc engine OHV was ‘sloped’ forward with the model being often referred to as the BSA Sloper, a term adopted by BSA when marketing the bike. The engine was a single exhaust port cylinder head with an aluminium casing enclosing the rockers with exposed valve springs. The pushrods were covered by nickel-plated tubes with later models having chrome replacing the nickel plating. The design of the cams and tappets resulted in a quiet engine (lack of valve clack) with some attributing the S meaning ‘silence’. The crankcase enclosed a large flywheel and a separate oil feeder tank. There was also a 350cc version in the range.
As with all motorcycles, there
