THE GREATEST YEARS OF THE ‘DESERT SLED’ were all too brief. For a few years in the 1960s, British twins became reliable enough to take on the worst that the California deserts could throw at them. Triumph, Matchless and Norton all produced two-wheeled devices for hooning about in the dirt on. But it was an unsung marketing genius at BSA who got their factory to produce something off the showroom floor that riders could ride seriously. BSA’s unit twin had been a new and different sort of motorcycle from the start. While British rivals either stumbled on with old pre-unit designs or aped their old looks with new unit twins, the BSA engine bore little resemblance to anything else coming out of UK factories.
The engines had styling that was more Italian than British, all smooth curves and polishable casings. The motor had fewer bolted-on bits to shake loose and fall off, and fewer jointing faces than its rivals, with a single rocker cover over the valves, one-piece barrels with integral pushrod tunnels which were short (as seen on the A7 and A10 twins), and long cylinder liners running down into the vertically split crankcase, making for an apparently short engine. There was a strong alloy one-piece primary drive cover and many other sleek additions. It was something of a shock for traditionalists, but away from oily-fingered motorcyclists, the comparative space-age looks were a media hit and the unit twin was a regular feature of Swinging Sixties UK films. The frame, a tidy twindowntube cradle affair, looked similar to the last of the A7s, and there was plenty of chrome.
