Above: Rollie Free's famous American record run at Bonneville on September 13, 1948 aboard an HRD V-Twin non-blown Vincent. First run just under the record, Rollie discarded his leathers and stripped down to speedos, swimming cap and borrowed tennis shoes for his final run. He removed the seat and laid down flat to avoid wind resistance and steered by staring down at the painted stripe. The above might just be the most famous motorcycle picture of all time (at least to motorcycle racing fans.) Instead of being killed, he tuned in an average speed of 150.313 for the then new American speed record for unstreamlined and unsupercharged bikes. WHAP! Take THAT!
This bike sold at auction in 2010 for a cool million dollars, the first motorcycle to ever fetch that price.
In 1949, a prize and trophy was offered for the first successful British attempt at the world record (held since 1937 by BMW at 173,54 mph.) NSU (Germany) upped the record to 180.29 mph in 1951. Vincent built a special brand new supercharged Black Lightning (below) which was then extensively modified for a British attempt at the record. In 1953, Les Graham was scheduled to make the attempt, but sadly Les was killed in a crash at the 1953 Senior Isle of Man TT. The supercharged virgin Vincent Black Lightning changed hands several times, but never made a record attempt.
The below picture is of the supercharged Black Lightning, itself an empty legend.