The specification and history of the twins
BSA prepared for Daytona is a subject we're still researching - the following should be
considered a piece of work in progress!
The twins BSA prepared for Daytona
followed a different evolutionary path from the Gold Star singles.
While the Gold Star was designed as a sports bike from the very
beginning, the Star Twin and Shooting Star twins were of humbler
design, intended to provide a bike that would take you to work and
back, day-in, day-out.
It's a mark of BSA's skill that the
final Daytona twins produced as much power as the Gold Star and
could go just as fast.
We think BSA first started preparing
twins for Daytona in 1952. These were the standard Star Twin
roadsters but with sports cams and carburettors and a great deal of
hand finishing and blueprinting during construction.
By 1953 the bikes were starting to
show changes made specifically to suit the unique nature of the then
beach race at Daytona. As with 1952 bikes these were Star
Twins carefully prepared but now fitted with shrouds over the rear
wheel to prevent sand blasting into the back of the carburettor.
1954 is the watershed year for the
twins. Reflecting BSA's increased commitment to the US market and
this race as a showcase for their products Roland Pike was tasked
with the development of both singles and twins for the 1954 Daytona
race.
Using many ideas he had earlier tried
on his own specials, Pike tested and built the bikes that won at
Daytona in 1954. The principal features of these bikes were :-
1954 twins - principal features
 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.
We believe much the same
speciifcation was used for the 1955
bikes with some small detail differences.
We're still not sure if twins were prepared for the 1956 but we're
pretty sure they weren't 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? |
