Fame and riches are fleeting things. Consider the BSA-Triumph group, which went from the thrill of victory at Daytona to the agony of insolvency in the short span of 14 months.
Shuffling deckchairs on the Titanic is the analogy that comes to mind. In 1971, the BSA-Triumph Group was effectively bankrupt. Through a period of astonishing ineptitude, the company lost its foothold in the only significant market it had left: the United States.
Yet that same year they fielded a factory team of 10 riders (including Dick Mann, Don Emde, Dave Aldana, Gene Romero, Gary Nixon, Mike Hailwood and Paul Smart!) on BSA and Triumph badged 750cc triples in order to wrest the Daytona 200 mile title from Honda. Mann won that race for BSA (as he had for Honda the year before) and went on to take the Grand National championship with a “Grand Slam,” winning every race in the series.
Until 1969, British motorcycles competing in AMA events were restricted by the organization’s 1933 (amended 1954) Class C equivalency formula, which required overhead valve engines to be under 500cc with a compression ratio of less than 7.5:1 (flathead engines were allowed up to 750cc), putting the OHV British bikes at a competitive disadvantage.
With the increasing importance of imports in the late 1960s, the AMA was forced to relax its rules to include all 750cc production-based bikes—just in time for Harley-Davidson to replace its ageing KR flathead with the new Sportster-based XR750.
So that still left BSA-Triumph floundering. The largest twin-cylinder bikes they produced— the 650cc Lightning and Bonneville—were giving away 100cc to the XR750. The 750cc three-cylinder BSA Rocket 3 and Triumph Trident were heavy, bulky motorcycles alongside the XR. And though Jim Rice among others enjoyed success with his Trackmaster-framed triple, it soon became apparent that a 750cc twin might fare better in Grand National flat-track races.
AMA Class C rules required competing machines to be based on production bikes. That meant BSA and/or Triumph would have to produce at least 200 750cc twins to homologate these machines for competition use, and not for the first time, it was Triumph’s east coast distributor, Tricor, that led the way.
Triumph had no intention of building a factory 750 twin, which they anticipated would take sales away from the recently-launched Trident. So, with aftermarket Triumph parts supplier Sonny Routt, Tricor service manager Rod Coates developed a conversion kit that could be fitted to the 650cc. Routt provided a cast iron barrel that appeared identical to the stock 650 item together with 76mm diameter pistons producing a 745cc displacement.
Two hundred Bonnevilles were converted at Tricor in Baltimore and at Triumph’s west coast distributor Johnson Motors in Duarte, California during 1969. Brand new bikes were partially uncrated, their stock cylinders removed and the 750 kit installed.
The suffix “T” was then added to the engine number—but not the frame.
Each buyer was required to sign a liability waiver acknowledging that their bike was an experimental model intended for competition events. (A factory 750cc Bonneville finally rolled out of Meriden in 1973.)
BSA, meanwhile, took a different approach. It wasn’t until 1971 that a 750 twin appeared, built at BSA’s Small Heath factory, though again only in a 200-unit homologation run.
The 1971 A70L was externally identical to the production A65L of the same year: only the tell-tale “750” decal on the side panels (and the engine number stamp) was different. Inside, the main change was a new crankshaft giving an 85mm stroke, with new rods to suit the longer crankshaft throws and new pistons giving 9.5:1 compression. The Amal 930 Concentric carbs also received a larger 250 main jet. BSA listed the crankcases as being new, though it’s not clear what the differences were from the A65L, apart from a change to accommodate a different timing side crankshaft bush.
Just 202 A70Ls were produced: 102 in June; 64 in July; and 36 in August of 1971. Estimates are that around 180 were shipped to BSA East Coast in Baltimore and with the remainder going to California. Curiously, the majority of the bikes had the 1972 black-painted frame, though at least one is known to have been finished in the ivory 1971 paint finish. All were listed as 1971 models, though August was officially the start of the 1972 model year.
It seems at least some of the A70s were dispersed around a number of US dealers, though many also were stripped of their engines, which ended up in flat-trackers. But the day of OHV parallel twins on the track was almost over. By 1974 Kenny Roberts, riding the fearsome TZ750 stroker, was cleaning up.
The A70 was never listed in BSA’s sales literature, and there’s no indication it would have replaced the A65 in BSA’s model lineup. In any case, events caught up with BSA during the following months. Barclays bank, now effectively running the company, pulled the plug, with production of BSA models ending in April 1972. From Daytona to dissolution had taken just 14 months!