Four stroke, single cylinder, SOHC, shaft and bevel gear driven, 2
valves per cylinder
Capacity
248.6 cc / 15.2 cu in
Bore x Stroke
74 x 57.8 mm
Compression Ratio
8.5:1
Cooling System
Air cooled
Induction
Dell'Orto SS1 29A carburetor
Ignition
Battery and coil
Starting
Kick
Max Power
17.2 kW / 23 hp @ 8200 rpm
Clutch
Multi wet plate, wet
Transmission
4 Speed
Final
Drive
Chain
Frame
Single cradle tubular frame
Front Suspension
Hydraulic telescopic fork
Rear Suspension
Swingarm, dual shocks
Front Brakes
Drum
Rear Brakes
Drum
Front Tyre
2.50 -19
Rear Tyre
2.75 -19
With production of the overhead camshaft singles well underway for 1958
the Formula 3 superseded the Marianna (the Gran Sport's nickname) as a
catalogued production racer. Offered initially as a 125 and 175 (and
from 1960 as a 250), the F3 was still largely based on the Marianna."
Almost nothing from the production street 250s was used in the F3 and as
further evidence of this uniqueness, virtually no engine gaskets were
interchangeable with the production OHC single. The UK version was known
as the 250 Manxman F3
The frame, although inspired by the road version, was quite different
being both lower and lighter, with a lower steering head, shorter 35mm
Marzocchi steel fork legs, and shorter swing arm, too. Plus 19in wheels
for the 250. The 175 motor would not fit the 125 frame, and come to
that, the 250 wouldn't go into either. "Although the F3s were genuine
factory racing machines they suffered through being too expensive for
most privateers, and were penalized by the 4-speed gearbox." Production
of all three capacity F3s together was very small, perhaps less than
100, with perhaps only as few as five or six 250s.
Source: Bonhams and Standard
Catalog of Ducati Motorcycles, 1946 - 2005, Ian Falloon