Uploaded October 2025 | Updated September 2026, 2 weeks ago
The 350 - 500 three-cylinder Grand Prix are racing motorcycles produced by the MV Agusta of Cascina Costa in the second half of the sixties. The supremacy of the MV Agusta in the world championship which, in the three-year period 1958 - 1960, had allowed it to grab the constructors 'and riders' titles in the 125, 250, 350 and 500 classes, was gradually crumbling after the arrival of the Japanese manufacturers Honda and Suzuki. . The initial strategy of the Varese manufacturer, to limit the damage to image, was the abandonment of the lower classes, but in 1962 Honda won its first championship in the 350 class, repeating itself in the following two years and starting to prepare for the climb to the premier class. The development potential of the 4-cylinder 500 engine designed in 1949 by Eng. Piero Remor with "cardano" final drive and revised in 1952 with the new gearbox and chain in engine / wheel traction were now minimal. Domenico Agusta decided at the end of the 1963 season to design a new three-cylinder engine with a displacement of 350 cm³. The guidelines of the new engine were dictated by Domenico Agusta not on a strictly technical basis but by using already tested solutions to save on development time.
The task was entrusted to the Director of the Technical Office Mr. Mario Rossi assisted by Arturo Magni, head of the racing department, who prepared the engine drawings in January 1964.
This was the scheme of the project:
- crankshaft group of the 500 four-cylinder
- two valve heads with needle springs
- lateral distribution folder
- ignition with points
- dry clutch
- 7-speed removable gearbox
The first bench tests highlighted the fragility of some choices in the distribution which were obviated by adopting a head with 4 valves instead of 2, controlled by helical springs. Legend has it that the prototype of the "350" was finished in August 1964. Count Agusta was informed of it during his summer stay in Venice and ordered that it be brought to him for viewing. According to this version, it was on the Lido beach that the progenitor of the MV tricilindriche was set in motion for the first time, to the amazement of the aristocratic vacationers. On the occasion, it seems that Domenico Agusta has communicated to Magni the decision to have the bike developed by an Italian rider, asking him to propose it. On the advice of his friend Ubbiali, Magni contacted a young rider with little experience in the world championship and proposed him to the patron who confirmed his candidacy: it was Giacomo Agostini. The delicate development work began at the end of 1964, aimed only at the version equipped with a 350 cm³ engine. The result was a bike that, compared to the four-cylinder, was more manageable, lighter and thanks to the smaller footprint of the three-cylinder engine, much more aerodynamic. The tireless testing work carried out by Agostini, supported by the Technical Management and the staff of the racing department, led to having the bike ready for the following season. The MV Agusta 350 3C GP made its debut at the West German Grand Prix at the Nürburgring, the second race of the 1965 season, driven by Giacomo Agostini; it immediately proved to be a successful bike, taking victory in the race and taking 2nd place in the world championship standings. It was therefore decided to increase the displacement to 500 cm³ for 1966. The project was led by Eng. Mario Rossi while the engine development was led by Ruggero Mazza. It was decided to proceed gradually and the first step was to increase the displacement to 400 cm³. The prototype took to the track during practice for the Dutch GP at the Assen circuit, obtaining immediate approval from Agostini. A second version, with an increased displacement again to 420 cm³, made its debut in the race in the East German GP and was the protagonist of the victories in the Finnish and Italian GPs which allowed Agostini to win the world title in 1966. Agostini always preferred this one. motorcycle to the 500 4-cylinder and with it won 7 of its 8 world titles in this class.
The 350 - 500 three-cylinder Grand Prix are racing motorcycles produced by the MV Agusta of Cascina Costa in the second half of the sixties. The supremacy of the MV Agusta in the world championship which, in the three-year period 1958 - 1960, had allowed it to grab the constructors 'and riders' titles in the 125, 250, 350 and 500 classes, was gradually crumbling after the arrival of the Japanese manufacturers Honda and Suzuki. . The initial strategy of the Varese manufacturer, to limit the damage to image, was the abandonment of the lower classes, but in 1962 Honda won its first championship in the 350 class, repeating itself in the following two years and starting to prepare for the climb to the premier class. The development potential of the 4-cylinder 500 engine designed in 1949 by Eng. Piero Remor with "cardano" final drive and revised in 1952 with the new gearbox and chain in engine / wheel traction were now minimal. Domenico Agusta decided at the end of the 1963 season to design a new three-cylinder engine with a displacement of 350 cm³. The guidelines of the new engine were dictated by Domenico Agusta not on a strictly technical basis but by using already tested solutions to save on development time.
The task was entrusted to the Director of the Technical Office Mr. Mario Rossi assisted by Arturo Magni, head of the racing department, who prepared the engine drawings in January 1964.
This was the scheme of the project:
- crankshaft group of the 500 four-cylinder
- two valve heads with needle springs
- lateral distribution folder
- ignition with points
- dry clutch
- 7-speed removable gearbox
The first bench tests highlighted the fragility of some choices in the distribution which were obviated by adopting a head with 4 valves instead of 2, controlled by helical springs. Legend has it that the prototype of the "350" was finished in August 1964. Count Agusta was informed of it during his summer stay in Venice and ordered that it be brought to him for viewing. According to this version, it was on the Lido beach that the progenitor of the MV tricilindriche was set in motion for the first time, to the amazement of the aristocratic vacationers. On the occasion, it seems that Domenico Agusta has communicated to Magni the decision to have the bike developed by an Italian rider, asking him to propose it. On the advice of his friend Ubbiali, Magni contacted a young rider with little experience in the world championship and proposed him to the patron who confirmed his candidacy: it was Giacomo Agostini. The delicate development work began at the end of 1964, aimed only at the version equipped with a 350 cm³ engine. The result was a bike that, compared to the four-cylinder, was more manageable, lighter and thanks to the smaller footprint of the three-cylinder engine, much more aerodynamic. The tireless testing work carried out by Agostini, supported by the Technical Management and the staff of the racing department, led to having the bike ready for the following season. The MV Agusta 350 3C GP made its debut at the West German Grand Prix at the Nürburgring, the second race of the 1965 season, driven by Giacomo Agostini; it immediately proved to be a successful bike, taking victory in the race and taking 2nd place in the world championship standings. It was therefore decided to increase the displacement to 500 cm³ for 1966. The project was led by Eng. Mario Rossi while the engine development was led by Ruggero Mazza. It was decided to proceed gradually and the first step was to increase the displacement to 400 cm³. The prototype took to the track during practice for the Dutch GP at the Assen circuit, obtaining immediate approval from Agostini. A second version, with an increased displacement again to 420 cm³, made its debut in the race in the East German GP and was the protagonist of the victories in the Finnish and Italian GPs which allowed Agostini to win the world title in 1966. Agostini always preferred this one. motorcycle to the 500 4-cylinder and with it won 7 of its 8 world titles in this class.
