B.S.A. 7.48 h.p. O.H.V. Twin £75.
A machine with an outstanding performance solo or sidecar. It has a vee-twin O. H. V. engine with 4-cam type valve gear with direct-acting push rods: dry sump lubrication ; 4-speed gear-box. etc.
Around 1600 Y13 models were produced of which perhaps as many as 40 remain (20 in the possession of just one person, it is rumoured). Originally built as a 499cc V-twin for military use, it did not enter service and became a civilian model, the J34-11, in 1934. This was designated the J34-12 in 1935 and ceased production in 1936. Introduced the same year, the Y13 750cc model remained in production until 1938.
Mounted in a cradle frame with girder forks, the engine has roller main bearings, dry sump lubrication, and a four-speed gearbox with high and low range for sidecar operation.
Instruments are housed in large panel atop the fuel tank, and the headlight may be fairly easily dismounted for nighttime repairs or camping.
BSA also produced a range of sidevalve V-twins dating back to the 770cc Model E of 1919. The last of these, the 986cc Model G, continued until the early post-war years.
A Y13 featured in the 1937 movie O.H.M.S.