From Wikimedia Commons, the free media repository
English: Custom motorcycles, built from a BSA engine in a Norton frame. Usually the engines were twin-cylinder but some were built with a Gold Star single-cylinder engine. This was cheaper than a Manx Norton engine and easier to maintain for the clubman racer. The name could be seen with variations on Norbsa such as Norsa, Norstar, Norbstar, NorBSA, NorBeesa, NorBeeza.