1971 BSA 750 A70 Lightning
Frame no. A70L/HE01128
Engine no. A70L/HE01128
Rarest of the unit-construction BSAs, and the biggest inline-twin the company ever made, the A70L, also known as the Lightning 75, was a so-called "homolgation special." While the AMA allowed overhead-valve engines a maximum displacement of 750cc for flat-track and road race competition, it also required that 200 production models be made before the engine was eligible. Thus the 650cc BSA A65 was at a disadvantage. To get around that, the factory stroked the design to 85mm, which also required a host on internal changes, and shipped the required 200 units (plus 2 just to be sure) over to the U.S.
Today, this most collectible of the latter-model BSAs is a rare find in complete shape, as many of the motors were removed to be fitted in purpose-built racing frames. Showing some use, the Lattin A70 nonetheless retains its original finishes and seat.