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BSA Star CI5T
BSA's lightweight singles of the 1960s
symptomised much of what was wrong with the British industry at the time. Yet
they provided transport for thousands of young riders, and the trials versions
helped usher in the modern era of off-road sport, while being very successful in
their own right.
BSA had acquired the Triumph marque at the start
of the 1950s, and the lightweights towards the end of the decade owed far more
to Triumph than to BSA. Chief among them was the 1958 C15 Star. A 250cc
fourstroke almost totally derived from the 200cc Triumph Tiger Cub. Even so, the
new model seemed both up-to-date and sophisticated, with its light weight and
sophisticated electrics.
As with its Triumph predecessors, the C15 and its
derivatives suffered from minor electrical problems, oil leaks and somewhat
complicated maintenance routines. But it went well enough and was mainly
reliable. The SS80 sports version, which appeared in 1961, was faster, while the
350 version, the B40, offered more power. In the mid 1960s a similar engine
layout was seen in the 75cc Beagle and 50cc Ariel Pixie, two fatally flawed
attempts by the BSA Group to launch an ultra-lightweight.
Over the years there were countless variations on
the same theme, including sports and off-road versions, while the basic engine
was stretched to 441 and finally 499cc. The engine even found its way back to
Triumph, to power the street-scrambler-styled singles of the late 1960s .
The last of BSA's C15 derivatives was the B50,
built until 1973. Even after this, the specialist company CCM of Bolton built
their own derivative of the B50 for off-road competition throughout the 1970s.
Off-road sport was long a speciality of BSA. In the post-war era, the 350 and
500 Gold Stars had been enormously successful trials and scrambles mounts, but
the company correctly anticipated the shift towards lighter, more manageable
machines.
The lightweight, unit-construction CI5 offered a
great deal of potential, and the competition shop soon developed successful
works specials ridden by expert rider and BSA employee Brian Martin.
Production versions followed the CI5S scrambler
and CI5T trials machine. Superficially similar to the roadsters, there were in
fact numerous differences, which included frames, wheels and suspension, as well
as a host of engine and gear modifications.
The competition bikes succeeded famously. On the 44Ice derivative, Jeff Smith
won the world motocross championship in 1964 and 1965. It was the design's
finest hour.
Specs
BSA CI5T (I960)
Years in production: 1958-73 , (CI5T 1959-65)
Engine type: single-cylinder ohv
four-stroke Bore and stroke: 67 x 70mm
Capacity: 247cc Compression ratio: 7:1 Power: 15bhp @ 5000rpm Carburettor: Amal
Monobloc
Exhaust high level Weight 2751 b Top speed: 75mph |
