Classics
Words & photos: Rhys Jones
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Extraordinary Euro twins
T
here is little doubt that in the history
of classic motorcycling twin-cylinder
engines have been the most prolific
of all motors. There has, however,
been a remarkable difference in the
configuration of the two cylinders.
The vertical, or parallel, twin seems
to be the most favoured, especially
by many British manufacturers.
Designers in continental Europe have seen
things differently, and three of them have been
responsible for twin cylinder engines that are very
distinctive. They are BMW, Moto Guzzi, and Ducati.
The first of these, BMW, dates back to 1920. A
foreman in the company stripped down a 1914
longitudinally-mounted Douglas flat twin, and
passed it to Max Friz who had designed the first
BMW motorcycle. Friz examined the Douglas and
designed the R32, a transverse flat-twin, launched
in 1923. This was the beginning of a long line of
transverse flat-twin R series engines which, following
many modifications, was still going over 70 years
later. The ‘Boxer’ BMW with the flat-twin cylinders
and shaft-drive has become one of the most
durable and admired motorcycles of all. Whether
it’s road racing, off-road, touring, or for every-
day use, the simplicity of the design allows the
engine to cover almost everything, even pulling a
sidecar – and during the Second World War BMW
produced an R75 motorcycle for the German
army. There are very few motorcycles as distinctive
and instantly recognisable as a BMW flat twin.
The other two twins are, of course, Italian, and
although they haven’t enjoyed the longevity of the
BMW design, they do have a great deal of charisma
and style. The Moto Guzzi V7 first appeared at the
Milan Show in 1965, but it wasn’t made available
until 1967. The V7 was so called because of the
V-twin motor, and a cubic capacity of 704cc. Like
the BMW, it was air-cooled and shaft driven, but
the configuration was a 90-degree transverse
V-twin rather than a flat twin. Some said it was
like a “BMW with the cylinders bent upwards
American V-Twins
car, but this didn’t proceed, and the concept
became the predecessor of the V7 motorcycle.
The V7 Special with the capacity increased to
758cc followed in 1969 with a claimed 45bhp at
6000rpm. In 1971 it became the V7 Sport with 30mm
Dell’Ortos and 52bhp. There was also a longer stroke
844cc 850GT. The transverse V-twins seemed to
increase their cubic capacity with every new model,
but in 1977 the factory produced two smaller
versions, the 500cc V50, and 346cc V35, both shaft
driven and air-cooled. The same distinctive engine
configuration has endured into the 21st century.
Unlike the BMW and Moto Guzzi, the Ducati, often
described as a V-twin, is actually an L-twin, so all
three bikes have differently configured twin cylinder
motors; transverse flat twin, a transverse V-twin,
and a longitudinal L-twin. In 1970 ace designer Fabio
Taglioni was given the task of designing a new
748cc L-shaped twin; the front cylinder not quite
horizontal, and the rear just as nearly vertical. The
result was the GT750 which entered production
the following year, and what could signal the
Ducati 750 trio: 750 GT, 750 Sport, 750 Super Sport
1975 Ducati 900SS L-twin engine
1976 Moto Guzzi transverse V-twin engine
at 45 degrees each”. In fact, the alternators on
some V7 twins are interchangeable with BMWs.
The low-stressed engine and comfortable power
delivery was ideal for use by the police and military.
The original design concept, then a 500cc motor,
was also considered for use in a small Fiat 500
Ducati 900SS 1975
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1975 BMW R90S transverse Flat-twin engine
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