Fast BSA twins

In the US BSA were selling larger capacity Indian and Harleys and there was pressure from dealers for BSA to produce not only larger but faster machines.

In what was the first example of a machine whose specification was created purely to satisfy the US market, BSA produced a super sports version of the Gold Flash called the Super Flash.

In small numbers (about 600) and for one year only BSA produced the 650cc Super Flash.

The Daytona beach races were the premier event in the US race calendar from 1947 to 1961. These races were held on a flat oval that was half beach, half tarmac – not at all like the present banked circuit that replaced the beach circuit in 1961.

Bikes raced in these events had to comply with AMA class ‘C’ regulations - see above. Though both Gold Stars and Star Twins had been competing in the Daytona beach races since 1949, the twins suffered from reliability problems and had not been very successful.

After a fact-finding mission to the US in 1951 BSA embarked on a programme of systematic development for both bikes that would ultimately benefit the racers too. Up until that time BSA’s approach had been to fix problems as they became apparent.

During another US fact-finding mission in 1953, US dealers asked BSA to produce a bike specifically for the American competition market.

They asked for a bike that could be used for both long 200 mile races like Daytona and short half-mile oval tracks. Roland Pike, then with BSA as a development engineer was given the go-ahead to produce a prototype.

He used a production welded trials frame with a rigid rear end, the new for 1954 Shooting Star alloy head, sports cam, alloy top yoke, rims and mudguards to poduce a biked that weighed less than 280lbs and could reach 116mph on the timing strip.

Eight of these rigid lightweight racers were entered at Daytona in 1954 - four singles and four twins - and with these BSA were in first eight places with twins the first three.

This result was the apogee of 500cc twin development and BSA didn’t manage anything like this success afterwards. This was due partly to Harley developing the the KR model introduced in 1953 into a winner.

It was also due to the departure of development head Bert Hopwood leaving BSA for AMC. With him went the motivation and impetus to develop the twins further.

Once at BSA, Pike favoured the Gold Star over the twins but felt after his earlier experiments that there was scope for improvement and built a prototype while at BSA.

It was a very smooth running engine, both on the dyno and on the road. Power output was similar to the Star Twin, using a 7.25:1 compression ratio. With further development and lighter valve gear it produced 36bhp at 7000rpm and with a two-into-one exhaust system as much as 39bhp.

Pike describes the bike as "... a most exciting machine to ride, as you accelerated it went on a normal power curve, then suddenly the exhaust note would change and it would 'yowl' right on up to maximum about 107mph." All this in 1953 on low octane petrol!

Pike claims that no-one in BSA showed any interest so the bike was run into the ground and forgotten about. His views about short stroke motors were vindicated though in subsequent decades as all manufacturers used short and even square cylinder dimensions.

That BSA produced a prototype OHC twin in 1938 to the Triumph Speed Twin is fairly well known. It is generally held that the prototype was lost during wartime bombing and that marked the end of OHC twin experiments until the 1960's.