The Second World War had barely finished when the Birmingham Small Arms Company introduced the iconic B31. A 350 cc four-stroke thumper propelled the bike to a top speed of around 70 mph, and although it was based on a pre-war design, the B31 remained in production until 1959. This hardtail custom is featured on the website of Speer Performance, a vintage motorcycle specialist based in Melbourne, Australia. Click here for more wonderful images from the mysterious Jim Atanasovski, including a Suzuki T500 post classic racer and 1948 Bedford truck on the salt flats.