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Ducati 125 Desmo (by Ian Falloon, Oct 2022) ![]() Pioneering
two-pot screamer
The
first indication that Ducati were interested in building
larger, multi-cylindered motorcycles came at the Milan
Show in December 1956, with the unveiling of a 175cc
double overhead camshaft parallel twin with exposed
valve springs. This
was raced in the final, 1957, Giro d’Italia by Leopoldo
Tartarini, but it retired in the 3rd stage. Dating from
drawings first sketched by Taglioni in 1950, it was an
interesting, if complicated design, with the pressed up
crankshaft consisting of two flywheel assemblies clamped
by Hirth (radially serrated) couplings. A
jackshaft was driven off the middle of the crankshaft
and this drove the twin overhead camshafts by a train of
spur gears. While the 49 x 46.6mm 175 produced
considerably more power than the 175cc single cylinder
Gran Sport at 22 bhp at 11,000rpm, the narrower power
band and increase in weight to 112kg (247 lb) largely
negated this benefit. The
175 became the basis for a 125cc Grand Prix machine
first raced by Franco Villa at the Italian Grand Prix at
Monza in 1958 where it finished third in that remarkable
Ducati 1-5 clean sweep. This
125 was intended to replace the single by producing more
horsepower through increased revs, and the 42.5 x 45mm
engine produced 22.5 bhp at 13,800rpm. A similar three
camshaft desmodromic valve system to the single allowed
the engine to rev to an amazing (for the time) 17,000
rpm, but the power band was extremely narrow and the
bike difficult to ride despite having a six-speed
gearbox. As with the 175 twin, the 125 was also too heavy at a claimed 92kg (203 lb), and the handling was less than satisfactory. Compared with the single, the twin (of which only three were built) didn’t achieve much success. Breakages in the camshaft drive gear train often occurred, with disastrous results, and the bikes were sold at the end of the 1959 season, two of which ended up being raced by Mike Hailwood.
With
a bore and stroke of 64 x 54mm, the 350 produced 48bhp,
but the engines vibrated badly and the bikes needed a
lot of development to be competitive. At the end of the
season John Surtees bought both Hailwood’s 250 and 350,
followed a few months later by Kavanagh’s.
------------------------------------------------- Produced by AllMoto abn 61 400 694 722 |
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