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BSA DAYTONA TWINS

52 twin in Cycle magazine feature, March 1952

1952 Twin shown at Daytona in 1953

1953 twin - BSA works photo

1953 twin - BSA works photo

1954 twin - BSA works photo

1954 twin - BSA works photo

1954 twin in BSA before despatch. Left to right, Arthur Lupton, Roland Pike, Len Crisp, Dennis Hardwicke

1955 twin - BSA works photo

1955 twin - BSA works photo

1955 twin in BSA before despatch. Left to right, Cyril Halliburn, Dennis Hardwicke, Len Crisp.

 

    

The following should be considered a piece of work in progress!

1952  
By 1952 BSA were starting to ship Star Twins specially prepared for the event to the US distributors.  Evidence from a recently restored example in the US shows a considerable amount of hand-finishing, polishing and lightening of engine internals  on these bikes in the competition shop.  

 

1953  
The specification of these bikes has been influenced by local race conditions - note the shrouding around the rear wheel to prevent the rider and carburettor getting sand-blasted.  

 

1954  
This is the first year there are any significant changes in specification reflecting the increased commitment made to the event by Bert Hopwood and Roland Pike.

Special rigid lightweight frame – BSA claimed to have made 100 or so for homologation purposes.
 Oil tank made by welding two tool-box halves together
 Fabricated alloy top yoke
 Sheet alloy shrouds around the rear wheel to protect from sand
 Vokes oil filter
 Front brake lever is reversed – allegedly better effect on the trailing shoe
 Longer front fork shrouds
 Daytona gearbox – stamped DAY
 Twin carburettor cylinder heads. The 54-55 stock A7ss was fitted with a twin port head but a bolt-on single piece manifold. Hopwood hoped to develop the twins into Gold Star beaters and kept a 2 carb option open for production bikes but used the same barrel for the Daytona racers, resolving the homologation issue.
 Thick-flange 6 fin barrel – this is slimmer in profile than the standard barrel and looks very similar to the earlier semi-unit type barrel. We believe this was fitted for reasons of strength though there is no evidence on the track that this was an issue. This was a special part but we have anecdotal evidence that these were available as service replacement spares from BSA later in the 1950’s– perhaps a batch was made for homologation purposes.
 Special 358 Daytona cam – this was available separately as a spare from US dealers and was copied by 3rd party UK manufacturers in the 60’s.

We believe that the Shooting Star engines did not receive the ‘Pike’ treatment – he was not a fan of the twins - and were basically stock with the above exceptions and expert hand-finishing from the competition shop fitters.

 

 

1955  
We believe the 1955 bikes were the same.

We believe the 1956 bikes had swing-arm frames but still had the 6 fin thick flange barrel.

We don't know if any twins were prepared in 1957. After Hopwood left BSA in 1955 the motivation to do anything with the twins – race or roadster – was gone.

And since BSAs directors already had a very successful sporting 500cc bike that sold in the US – the Gold Star – why complicate the marketing message with another?