Motorcycle Investor mag Subscribe to our free email news
Ducati 125 Sport (by Ian Falloon, Feb 2022) ![]() The
market's desire for racer-replica Ducatis has a long
history Ducati’s reputation
has always been built on racing success, and it began
back in 1955 with the
100cc Gran Sport. After the Laverdas
soundly beat the overhead valve Ducati 98s in the 1954
Motogiro d’Italia and
Milano-Taranto road races, Ducati lured the great
engineer Ing. Fabio Taglioni
away from Mondial and commissioned him to design a new
motorcycle capable of
winning the 1955 Motogiro. The result was the
magnificent Gran Sport, or Marianna. This advanced
design formed the basis of
the all the overhead camshaft singles through until
1974, with many of its
design characteristics continuing to feature on some of
the current engines. After the humiliation
of 1954, no-one could have predicted the success of the
Marianna in the 1955
Motogiro d’Italia. The Mariannas were
unbeatable, Taglioni’s one-year contract was extended,
and his association with
Ducati would last four decades. The basis of the Gran
Sport engine was its vertically split aluminium unit
construction crankcase,
aluminium cylinder (with cast-iron liner) inclined
forward 10 degrees, a single
overhead camshaft driven by a set of bevel gears from
the crankshaft, and two
valves set at an included angle of 80 degrees. All the bearings were
ball or roller and incorporated in the crankcases was a
four-speed gearbox,
driven by primary gears with a wet multi-plate clutch.
Ignition was by battery
and coil with the points driven off the lower bevel gear
on the right. This
engine was then placed in a single downtube tubular
steel frame and was
utilised as a stressed member, all these features making
their way to the
eventual production version, most also evident on all
single and twin cylinder
Ducatis though until 1980. The success of the
Gran Sport was such that Taglioni was allowed to adapt
his advanced single
cylinder overhead camshaft engine for production.
Initially 175cc, most
motorcycles of the period still featured overhead valves
operated by pushrods,
and while there was little to separate the OHV 98s and
125s from dozens of
other Italian motorcycles available at the time, the
overhead camshaft 175
provided exceptional performance. The 175 was first
displayed at the end of 1956, and its success, they
accounted for 25 per cent
of 175 cc sales in Italy during 1957, saw a
proliferation of overhead camshaft
models during the next few years. Only a year after the
introduction of the 175, the 125 Sport (1962 model
pictured) was offered.
Sharing its 55.25mm bore and 52mm stroke with the double
overhead camshaft
Grand Prix and desmodromic racers, the 125 Sport had an
8:1 compression ratio
and Dell’Orto 20mm carburettor and produced a modest 10
horsepower at 8500 rpm.
T his may not have
sounded much but the specific power output of 80
horsepower per litre was quite
impressive for a production engine in 1958. Rolling on a
pair of 17-inch wheels
the diminutive 100kg 125 Sport was capable of around
112km/h, quite a bit more
than most 125s at the time. As the styling,
particularly the sculptured 17-litre fuel tank, mimicked
the racing 125 F3, the
125 Sport became favoured with the Italian boy racer
crowd. This was the first
production Ducati that looked like the racing bikes and
established a formula
that has served Ducati well for over sixty years. As the 125 Sport was
proving successful, a low compression 125 TS (Touring
Special) joined it later in
1958 but this wasn’t what the market really wanted. The
125 eventually became a
160 but as this was perceived as an underpowered 175 it
languished, eventually
becoming the unremarkable 160 Monza Junior. Although the 125 Sport
remained a popular model, particularly in Italy, through
until 1965, the
writing was on the wall for the smaller capacity
Ducatis. The public then, as
now, wanted larger engines, with more performance, but
what hasn’t changed is
their thirst for factory race replicas. ------------------------------------------------- Produced by AllMoto abn 61 400 694 722 |
ArchivesContact
|