The BSA D1 125cc engine unit began production in 1948 for export only. The design had been taken from the German firm DKW as part of the war reperations. The engine proved itself, and with small motorcycles becomming ever more popular in Britain, BSA decided to build a complete motorcycle around the D1 engine.



The lighting was supplied by a 27 Watt Wico-Pacy Geni-mag generator, direct electrics meant no battery, and that the engine would have to be running for the main lights to work. A small battery was included to operate a smaller pilot bulb in the headlamp when parked. Ignition was supplied from the same unit, in the form of a simple Magneto, this also eliminated the need for a battery. Although the bike had its fair share of faults, it sold well and became a common sight on the Roads of Britain. One thing BSA motorcycle had not expected, was its introduction into competition events. Owners modified their bantams, fitting non-standard sprockets and wider handlebars. The Bantam was one of the first bikes to be used in this way, trials before that had been more professional events run by substantially larger bikes.



The BSA D1 Bantam was one of the most successful lightweight bikes ever to be built in the UK. BSA launched the Bantam D1 in March 1948 and the first production bike was ready in June of that year. Its 3-speed, unit construction engine was a mirror-image of the DKW RT125, adapted to suit BSAs non-metric machine tools and the British inclination towards big flywheels from the designs handed over as war reparations. More specs and user manual of BSA Bantam you can see in next overview.