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Motorcycle Investor mag

Ducati Singles

(by Ian Falloon, Mar 2022)

Looking back to simpler times

While Ducati is largely characterised by their adherence to the 90-degree L or V-twin, this wasn’t always so. For their first twenty-five years Ducati only produced singles, and these were varied. An eclectic range of two-stroke, pullrod, pushrod and overhead camshaft four-stroke singles sustained Ducati throughout the 1950s and 1960s. And at the top of the pile were a small number of limited edition catalogue racers available only to those with “factory connections.”

In the early 1950s most Italian manufacturers saw racing as pivotal for sales, but initially Ducati only produced small capacity motorcycles based on the Cucciolo clip-on engine. Seeking victory in the 1955 Motogiro d’Italia road race Ducati’s managing director Dott. Giuseppe Montano hired Ing. Fabio Taglioni to design a completely new motorcycle. The resulting 100cc Gran Sport was the first Ducati designed and built with racing in mind, and its success ensured that racing would become a predominant feature in the company’s history.

Taglioni always worked with surprising speed and showed a remarkable ability to get designs right the first time. Few engines exemplified this more than the Gran Sport, later nicknamed the Marianna. Conceived for racing first and production second it proved virtually unbeatable in the Italian road races, and formed the basis of the Grand Prix desmodromic racers and a range of racing and production singles through until 1974. Many of its design criteria carried through to the later 90-degree V-twins. Even some current engines, notably the two-valve twins and Testastretta owe much to the Marianna.

The Marianna’s success saw Ducati grow to become one of the largest motorcycle manufacturers in Italy. By 1955 production levels were around 20,000 a year and employees numbered more than 700 so there was justification for an escalation of racing development. Not content with their victories in the MSDS (macchine sport derivate dalla serie) category for production sports machines, Montano and Taglioni wanted to win the modified sports machine class. For this Taglioni created the Bialbero, or double camshaft, 125 Grand Prix, officially unveiled on 25 February 1956.

Apart from the cylinder head and an additional fifth gear, the Bialbero was ostensibly a Marianna, the twin overhead camshaft layout providing around 16 horsepower and revving to 11,500 rpm. With a handlebar fairing and streamlined seat the top speed was around 170 km/h. The basic chassis was also that of a Marianna, but with larger magnesium Amadoro brakes. But the Bialbero was outclassed in the 1956 Italian Championships events and Taglioni turned to desmodromic valves on the factory machines. This left the Bialbero as a catalogued racer available to privateers in limited quantities.

For 1957 the Bialbero received a new cylinder head casting, with a distinctive polished alloy gear cover. It may have been outclassed in Grand Prix racing but as a privateer racer the 125 Bialbero was incredibly successful. In England during 1958 Fron Purslow won a succession of races, this carrying on with Mike Hailwood after he purchased Purslow’s machine.

125 Championship victories were scored on Bialberos between 1957 to 1959 in countries as diverse as Holland, Switzerland, Brazil, Venezuela and Sweden. After the factory officially retired from Grand Prix racing at the end of 1959 some of the works 125 Desmos had their Desmo cylinder heads substituted with Bialbero cylinder heads and some Bialberos were built with four-speed Formula 3 crankcases. Sold to privateers, these were successfully raced for many more years.

The two Biaberos in this collection are both 1957 examples, the red bike presumably ridden by one of Ducati’s star riders of the 1950s, Leopoldo Tartarini. Tartarini later went on to found Italjet. Ricardo Fargas, a leading Spanish Ducati rider during the 1960s, raced the silver 125 Bialbero in Spain. While possibly fifty Biaberos were produced, only a handful survives.

As official factory involvement in Grand Prix racing gradually diminished, Ducati looked to the Italian championships for racing glory. Although Ducati was strongly committed to Grand Prix racing during 1958 the release and sales success of the 175 Sport in 1957 resulted in more emphasis on developing the production range. So for the budding privateer, two Formula 3 catalogue racers, the 125 and 175 F3, were offered in 1958 and were subsequently available as catalogue models for 1959. At the time these were extraordinarily expensive, the 125 more than a 500cc Matchless G50, so only a few were sold.

The 125 Formula 3 was ostensibly an evolution of the 125 Marianna. The sand-cast crankcases were similar, but were smooth cast without finning on the sump, as on the 125 Sport. But in just about every respect the 125 Formula 3 was different to the production 125 Sport. Shared with the Marianna were the four-speed gearbox, and straight-cut primary gears and bevel gears. Unique to the F3 were mirror image rocker covers, different camshaft covers and shorter camshafts. As on the Marianna the sand-cast F3 cylinder head had the exhaust retained by studs. An indication of the F3’s uniqueness was virtually none of the engine gaskets were interchangeable with a production overhead camshaft single.

Although patterned after that on the road versions, the single downtube frame was also quite different. It was lighter and lower, with a lower steering head, shorter swingarm, and a shorter 35mm fork. Despite their obvious race orientation, most F3’s also came with complete street equipment that included a headlight, muffler, taillight, horn, number plate holder, and centre-stand. The 125 F3 was particularly successful during 1963, winning national 125 titles in Italy, Canada, Argentina and Switzerland. This was repeated in Italy during 1964, 125 F3s still winning Italian 125cc events through 1966.

Along with the 125 F3 a larger 175 F3 was also available from mid-1958.

Although it looked similar the 175 F3 differed significantly to the 125 and also shared virtually nothing with the production 175 Sport. The 175 F3 crankcases included a wider front engine mount and as on the 125 the cylinder head was also quite different to the production 175, with mirror image rocker covers and specific cam bearing housings. The 175 F3 frame followed the style of the 125 F3, with the updated swingarm pivot and pinch bolts, but was slightly taller, with a longer 35mm fork. The 175 F3 shared the 125’s 18-inch wheels but now included the same Amadori twin scoop 180mm magnesium front brake as on most Bialbero 125 Grand Prix machines.

The 175 F3’s first major success was at Monza in 1958 in the 175 F3 support race for the Nations Grand Prix. Here Franco Villa rode a factory-prepared 175 F3 to win at an average speed of 142.005 km/h. This result heralded the beginning of a reasonably successful racing career for these beautiful little machines. After Villa’s success at Monza in 1958, Franco Farnè, accompanied by mechanic Ugo Mastroela, travelled to America.

Farnè’s specific purpose was to promote the new range of production overhead camshaft singles in the US. Farnè was spectacularly successful and rode the 175 to victory in the 1959 250cc event at Daytona, following this with seven more victories throughout the US and Canada until he returned to Italy in July.

During 1961 the production overhead camshaft single grew to 250cc and Ducati offered a limited number of 250 Formula 3s alongside the regular 250 Diana. These looked similar to the Diana, but as with all F3s virtually no parts were interchangeable.

Unlike the 125 and 175 the 250 cylinder head also came with bosses for desmodromic closing rocker spindles and some factory-supplied examples had a desmodromic cylinder head. The carburettor was now a larger Dell’Orto SSI 29A and the 250 F3 produced a claimed 23 horsepower at 8,200 rpm. Although similar to the 175 F3, the 250 engine would still fit a 175 F3 frame, the single downtube 250 F3 frame differed in details.

The swingarm was longer the wheels 19-inch. The front brake for 1961 was a 200mm Amadori with twin air scoops, similar to the 175 F3 but slightly larger. As the 250 F3 was larger and heavier than the 175 F3 it didn’t achieve the same success or endear an equivalent following. Intended for larger framed American riders it was arguably overweight, offering little advantage over a well-prepared Diana Mark 3 for considerably less outlay.

Ducati took the limited edition factory racer to another level in 1965 with the release of the 250 and 350 SC (Sport Corsa). The SC (Sport Corsa) was a factory racer, built in extremely limited numbers, one of the first travelling to Sebring with Franco Farnè for an FIM sanctioned event following Daytona in March. Run in conjunction with the famous 12-hour sports car race, Farnè not only won the 350cc class but finished 10th overall.

The wider sand-cast crankcases were designed to accommodate the double cradle frame and included a significantly wider rear engine mount than the production models and previous F3. Inside the crankcases was a close ratio five-speed gearbox and straight-cut primary gears. Ignition was by twin spark plugs, and carburetion for the 250 SC was a Dell’Orto SSI 30A. Ducati claimed 34 horsepower at 8,500rpm. For 1966 the 250 SC received a few updates. 200mm Oldani brakes front and rear replaced the Grimeca, and a 14.5 litre fibreglass tank and humpback solo seat fitted.

The essential dimensions were unchanged and while the 1,320mm wheelbase was moderate, the 250’s 115kg was excessive. Ducati no longer provided optimistic power figures, instead they claimed a top speed of 190 km/h for the 250 SC.

The SCs were undoubtedly extremely beautiful creations but were too heavy and the double cradle frame offered little advantage over the standard single downtube type. They weren’t spectacularly successful but paved the way for the next racer, the SCD (Sport Corsa Desmo). This would see the singles out until 1972. By this time there was no future for the four-stroke single in international road racing.

Ducati
singles