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Race Bikes for sale
Formula 750
Ray Petty Manx detail
competitive in the late 1950s and into the 1960s.
At the end of the 1954 racing season Bob McIntyre,
five-time Grand Prix winner and triple Isle of Man
TT winner, returned to riding as a privateer. In those
days short circuit road races were held almost on a
weekly basis and riders could finance themselves on
the start money and winnings. It was an advantage
to be able to compete in as many classes as
possible so McIntyre and his sponsor, fellow Scot
Joe Potts, developed a 250cc Manx Norton to
complement the 350 and 500 Norton entries.
The 250 Potts Norton was based on a 349cc Manx
reduced to an ultra short stroke engine of 64mm x
70mm bore. The cycle parts came from the
Norton spares list.
McIntyre rode the Potts 250 Norton Special in the
1956 and 1957 season with considerable success
including the British 250 Championship at Thruxton
and Silverstone in 1956. Without streamlining the
250 was capable of 100mph (160km/h), developing
its peak power at 8000rpm. Plans were to produce
a Desmo head for the 250, 350 and 500 Potts
Nortons for the 1958 season but this did not come
to fruition. McIntyre was killed after a crash on an
experimental five-speed Norton three years later.
In New Zealand the Desmo head idea
flourished in the hands of Brian Thomas. He
built a 250 Desmo Manx that won convincingly
at the 1998 Assen Classic, and he went on to
build 350 and 500 Desmo motors. Brian had
collaborated with Doug Hele, who had built a
Desmo head in the Norton workshop in 1958.
The fact that a single cylinder racing machine
with a heritage dating back as far as the 1930s
has inspired so much development, experimental
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