1966 BSA SPITFIRE
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outright disappointing. The much-vaunted racing front brake was suited for the high temperatures and speeds encountered on a race track. It worked best when individually fine-tuned with the linings skimmed true and the leading edge carefully feathered. And although ‘190mm’ sounds huge, it’s roughly 7.5 inches in old money… which gave much the same swept area as the normal brake fitted to BSA’s other 650 twins. The fins and vanes look impressive but several testers found it to be more about appearance than efficiency. ‘Not only was it not very powerful,’ said Cycle World, ‘but it squeaked badly at low speeds and set up a ferocious juddering if used at all hard at anything over 45mph.’
The racing brake gave the Mechanics test rider ‘some nasty moments. It seemed to require unduly severe hand pressure before it really began to function.’ In dry conditions on clean tarmac – perfect circumstances – the Spitfire took an entire 32ft to come to a halt from 30mph. Meanwhile, the standard roadgoing Lightning, which used the firm’s basic brakes, squealed to a stop from the same speed in just 26ft. So much for the racing brake’s ‘positive cooling and large lining area which makes for quick, straight- line stops.’ If BSA wanted to live up to their marketing hype then they’d need to make some changes to the Spitfire spec.
For despite the different approaches adopted to market the Spitfire on either side of the Atlantic (see sidebar) it was very much being sold as a street scrambler or highspeed roadster, not an outright competition machine or clubman’s racer. The super-sports class had been born and BSA promised a motorcycle ‘for the enthusiast who wants the best, the very ultimate in zestful performance and in sheer power.’ The mass market wouldn’t buy a bad-tempered beast of a bike. So the Spitfire had to be civilised.
The first stage came in 1967 for the MkIII with a pair of concentrics, which instantly resolved most of issues with the GP carbs. ‘Amal appear to have overcome the problem of ensuring a reliable low speed tickover with a high performance carburettor’ said Mechanics, welcoming a steady tickover and much improved low-rev and mid-range performance. However, the Spitfire would no longer live up to its high speed reputation. ‘ The test bike could never be persuaded to go much above the ton, despite efforts to get the new concentrics correctly tuned.’ 105mph