AJS 1912 Model B 2½ HP 315 cc 1 cyl sv 3606

AJS 1912 “Model B” 2 ½ HP 315 cc side valve single frame # 636 engine # 1696 gearbox # 296

The Stevens brothers Harry, George, Joe Junior and Jack had been in motorcycle engine manufacturing for various clients since the final years of the 19th century. In the course of 1909 it was decided to start building complete motorcycles under their own name. In 1910 two models were developed and built, Model A with direct belt drive and model B with chain drive and 2-speed gearbox with cork inserted clutch. Both models shared the same lightweight engine with bore x stroke dimensions of 70 x 76 mm, giving 292 cc. Production costs were largely met by Harry Stevens, from money paid to him by John Marston for designing a 349 cc engine that was destined for the first Sunbeam motorcycle. (Source: Stephen Mills, AJS of Wolverhampton) The newly designed machines were exhibited at the Olympia show in November 1910 and attracted much attention and praise. Especially the model B was an innovative machine, with its all-chain drive, 2-speed gearbox and dropped top tube to give a lower seating position. The machines had a good performance and weighed around 90 kg.
For model year 1912 the stroke was increased to 82 mm, which brought the capacity to 315 cc. Model year 1913 saw the discontinuing of the belt drive model A and again enlarging the engine capacity of the model B to 349 cc by increasing the stroke to 91 mm. Now there was a choice of two or three-speed gearbox and each machine now had fully enclosed chain drive: the 1912 models had an enclosed primary chain with a chain guard to the front part of the driving chain.
The company first entered the Isle of Man TT in 1911, making an historic breakthrough in 1914 when it won the Junior event, the first such victory by a single-cylinder machine. From then onwards the 2¾hp (349 cc) side valve-engined model remained a fixture of the AJS range.
The machine we present has been in the former owner’s possession since December 1988, as witnesses by a purchase invoice from Brian Verrall. She comes with Pioneer Certificate, and, according to the Register of Machines of the VMCC, has the third oldest recorded frame number of veteran AJS machines. Photocopied literature on file includes copies of The Motor Cycle, 16th November 1911, together with various photocopied period advertisements and contemporary articles.
This very early AJS is accommodated with Bosch magneto and Amac carburettor. She has been part of a private collection for almost 40 years and she’s in running condition. Few veteran era machines are fitted with a countershaft gearbox and clutch, which makes this AJS an interesting choice for enthousiasts.