Miniature Marvel: Inside the Ducati 125cc GP Four

Giancarlo Morbidelli locates a Ducati 125cc GP four prototype’s missing pieces and painstakingly restores it to original condition.

| January/February 2019

  • First sketched out on paper by Fabio Taglioni in the 1950s, then half-heartedly developed to a semi-prototype stage in 1958, the project was revived in 1965.
    Photo by Phil Aynsley
  • Although Ducati achieved GP wins with its 125cc single in 1958, with Ducati riders finishing second and third in the championship and the factory second in the constructors’ championship, the 125cc 4-cylinder project was dropped, and Ducati went into a kind of domestic hibernation while it concentrated on selling existing models into new export markets.
    Photo by Phil Aynsley
  • The four condensers on the outside of the points case.
    Photo by Phil Aynsley
  • The theory that created the birth of an amazing prototype was that a higher-revving multi-cylinder could produce more than the 24 horsepower at 15,000rpm of the twin.
    Photo by Phil Aynsley
  • The 125 GP during restoration at the Morbidelli museum in Pesaro, Italy.
    Photo by Phil Aynsley
  • Taglioni’s 125cc four wasn’t some cobbled-together prototype, but a beautifully assembled miniature marvel featuring exquisite castings and a general design flair that is breathtaking, even by today’s standards of technology.
    Photo by Phil Aynsley
  • Giancarlo Morbidelli (left) and photographer Phil Aynsley with the 125GP four.
    Photo by Phil Aynsley
  • One wing of the museum is dedicated to Morbidelli race bikes.
    Photo by Phil Aynsley
  • Giancarlo Morbidelli and his Morbidelli V8 sport tourer.
    Photo by Phil Aynsley
  • Although Italian sport and racing machinery takes pride of place — there’s an incredible presentation of Morbidelli race bikes in a special side alcove — the 400-strong collection represents bikes from around the world, including special prototypes and other one-offs.
    Photo by Phil Aynsley

Engine: 125cc air-cooled DOHC 4 valves per cylinder inline four, 34.5mm x 34mm bore and stroke, 12:1 compression ratio, 23hp @ 15,000rpm
Top speed: 125mph
Carburetion: Four 12mm Dell’Orto (originally; 16mm now fitted), twin floats/one per pair of carburetors
Transmission: 8-speed, chain final drive
Electrics: 6v battery, coil and breaker point ignition x 4
Frame: Dual downtube cradle steel
Suspension: 32mm Ceriani telescopic fork front, dual shocks w/adjustable preload rear
Brakes: Oldani TLS drum front, SLS drum rear
Tires: 2.5 x 18in front and rear
Weight (dry/minus fairing): 187lb (85kg)

One of the most intriguing chapters in the history of multi-cylinder Grand Prix racing is Ducati’s 125cc 4-cylinder. First sketched out on paper by Fabio Taglioni in the 1950s, then half-heartedly developed to a semi-prototype stage in 1958, the project was revived in 1965.

It underwent a year of testing and development, but was never raced. After being sent around the motorcycle show circuit it mysteriously disappeared. In 1989 the engine was discovered in Latvia and later the frame uncovered in Yugoslavia. In 2000 the machine was restored back to original condition and it now resides in the Morbidelli Museum in Pesaro, Italy.

What were the circumstances that led to its creation? What made it so special in Ducati’s history but so quickly forgotten? Was it a potential world beater?



A pure racer

There are several fascinating aspects to the 125cc 4-cylinder. The most significant is that it was designed purely for racing and bore no resemblance to any production Ducati. This showed Ducati’s clear intent to break away from production-based racing, which had set it on a path to worldwide sales success, and chase Grand Prix glory. Ducati was hoping to up the stakes with a clean-sheet design.

Ducati’s timing with its original foray into building a 125cc multi couldn’t have been worse. To begin with, Fiat’s introduction of the affordable Fiat 500 car was crippling domestic motorcycle sales, then, at the end of 1957 Italian Grand Prix powerhouses Gilera, Moto Guzzi and Mondial announced they would withdraw from world championship racing, altering the face of Italian competition. Although Ducati achieved GP wins with its 125cc single in 1958, with Ducati riders finishing second and third in the championship and the factory second in the constructors’ championship, the 125cc 4-cylinder project was dropped, and Ducati went into a kind of domestic hibernation while it concentrated on selling existing models into new export markets.



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