The MV Agusta 350 cc racers were motorcycles produced by MV Agusta between 1954 and 1976 and raced in the 350 cc motorcycle GP championships. 10 world titles were achieved by riders John Surtees, Gary Hocking and Giacomo Agostini on these machines.

MV Agusta 350 4C 1954–1964 Count Domenico Agusta never released technical data of his machines and personnel, technical staff and riders were forbidden to divulge anything about the machines. Because a number of newer machines were later sold through auctions, data is known about these, but the machines from the early years sometimes remain a mystery. Of the original 350 4C is really only known that it was a reduced version of the MV Agusta 500 4C. Designer Piero Remor initially provided that machine with experimental and often useless technology, but rider Leslie Graham made some improvements. In 1953 that machine had a telescopic forks and a double cradle frame. It had a Four-stroke transverse in-line four-cylinder engine with DOHC with two valves per cylinder.

Technical data MV Agusta 350 4C 1954–1964 MV Agusta 350 4C19541955195619571958195919601961196219631964ValvetrainDOHC with two valves per cylinderEngine configurationFour-stroke transverse in-line four-cylinder engineEngine coolingAir coolingBore47.5 mmStroke49.3 mmEngine displacement349 ccLubrication systemWet sumpCarburetors4 Dell'Orto SSI 28AMax powerc. @ 12,000 rpmTop speed Primary driveGearClutchWet multi-plateGears5Final driveChain driveFrameDouble cradleFront forksTelescopic forksRear forksSwingarmBrakesDrum brakes

Results 1954–1964 1954 Bill Lomas and Dickie Dale received MV Agustas for the 500 cc Senior TT on the Isle of Man, but also started with the 350 cc version in the Junior TT. It was not a success: Lomas was only 7th and Dale was 25th. For the time being, MV Agusta still had to bow to the AJS 7R and the Norton Manx.

1955 In 1955 the 350 cc MV Agustas did not start in GPs, possibly because they were concentrating on the 250 cc class.

1956 When John Surtees came to MV Agusta in 1956, he brought his knowledge of the Norton Featherbed frame with him. The improvements to the 500 cc MV Agusta were also applied to the 350 cc four-cylinder. Surtees finished second in the 350 cc TT in Assen and won the Grand Prix of Belgium, but after a nasty fall in the Grand Prix of Germany, breaking an arm, he was eliminated for the rest of the season. Umberto Masetti rode a send MV in the Belgian and Nations Grand Prix at Monza. Carlo Bandirola also raced an MV at Monza. Surtees finished fourth in the 350 cc world championship.

1957 Surtees drove the MV Agusta 350 four-cylinder in almost all the 1957 GPs, but the machine was hopelessly unreliable. He finished fourth in the Junior TT, but dropped out in five other GPs. He finished 10th in the Championship.

1958 At the end of 1957, the Italian brands Gilera, FB Mondial, Moto Guzzi and MV Agusta announced that they would stop road racing. Racing was simply too expensive, especially for the companies that had to live off motorcycle sales. For Count Domenico Agusta however, the situation was different. He earned his money by building helicopters and motorcycles were just a hobby. With the loss of the biggest competitors (the British brands had stopped earlier), the fortunes for MV Agusta turned. The development of new prototypes was stopped, because it was clear that the four-cylinder MV Agusta would now be strong enough for the world title. That turned out to be the case in 1958: the brand won all the world titles in the solo classes, including the manufacturer's titles. Surtees won all six 350 cc races he started in, and won the championship. John Hartle was runner-up in the world championship as MV's second rider.

1959 In 1959 John Surtees won all six of the GPs and the Championship. Again his teammate John Hartle was runner-up in the world championship.

1960 The 1960 season was exciting due to the battle between the two teammates from MV Agusta, John Surtees and Gary Hocking. Both riders finished with 22 points. They both had two wins and one second place. Surtees had also achieved third place, which made Surtees world champion. At the end of the season John Surtees left to pursue a Formula One career.Adam Cooper, Obituary: John Surtees, 1934–2017, www.motorsport.com Retrieved 12 March 2017

1961 In 1961, Gary Hocking was the sole rider for MV Agusta in the 350 cc class. He skipped the first race (Germany) but then started collecting points. He was second in the Junior TT, and this was followed by victories in the Netherlands, the GDR, Ulster and Italy. He missed the last Grand Prix in Sweden, as his world title was already won by then.

1962 In 1961 Honda had not competed in the 350 cc class, but for the 1962 season the Honda RC 162 was bored out to 284.5 cc and designated RC 170. Bob McIntyre and Tom Phillis rode the machine in the Junior TT. Phillis crashed during that race and McIntyre retired. Mike Hailwood won the race with the MV Agusta. He was second in the TT of Assen and the Grand Prix of the GDR, but the Hondas won all the races and Jim Redman (Honda) became world champion ahead of Tommy Robb (Honda) and Mike Hailwood (MV Agusta).

1963 Honda took a step back in 1963 and no new models were introduced. After the Ulster GP the mechanics were called back to Japan. Hailwood then won in the GDR and in Finland, but by then the world title was already decided in favour of Jim Redman and Honda.

1964 In 1964, MV Agusta focused primarily on the 500 cc class, where there was still no significant opposition. In the 350 cc class, Hailwood only started in Assen where he finished second.

MV Agusta 350 3C 1965–1973 In 1965 the new three-cylinder MV Agusta appeared. Count Agusta had wanted a 350 cc three-cylinder because he was impressed by the three-cylinder two-stroke DKW RM 350. Arturo Magni and designer Mario Rossi tried to dissuade him, but the count insisted.Statement from manufacturer Arturo Magni to journalist Carlo Perelli, summer 1993, published in Moto 73 No. 13 of 1993 He even suggested adding an extra cylinder to the MV Agusta 250 Bicilindrica. When the three-cylinder engine seemed ready, Count Agusta was displeased because there were only two valves per cylinder. Within a week the technicians converted the engine to four valves per cylinder and that immediately yielded an extra 6 horsepower. In 1966 a version with the engine enlarged to 420 cc was produced for the 500 cc class.

Technical data MV Agusta 350 3C MV Agusta 350 3C196519661967196819691970197119721973ValvetrainDOHC with four valves per cylinderEngine configurationFour-stroke transverse in-line three-cylinder engineEngine coolingAir coolingBore55 mmStroke49 mmEngine displacement349 ccLubrication systemWet sumpCarburetors3 x Dell'Orto 28 mmMax power @ 13.500 tpm @ 14.000 - 15.000 rpmTop speed Primary driveGearsClutchDry multi-plateGears76Final driveChain DriveFrameDouble cradleFront forksTelescopic forkRear forksSwingarmBrakesDrum brakes

Results 1965–1973 1965 In 1965 MV Agusta used the new 350 three-cylinder engine, but reliability was a problem. MV had two top drivers: Mike Hailwood and Giacomo Agostini, who took points off each other, while Honda put everything on Jim Redman. In the first 350 cc race of 1965 at the Nürburgring, Agostini won ahead of his teammate Hailwood and Gustav Havel on a Jawa, while Redman (Honda) crashed in the rain and broke his collarbone. During the Junior TT, Redman was out for his third win in a row, but Hailwood led by 20 seconds after the opening round with the new MV three-cylinder. He then made a long pit stop, allowing Redman to take the lead. The MV Agusta of Hailwood stopped at Sarah's Cottage on the fourth lap, giving Redman the win. Phil Read was second with the 250 cc Yamaha and Agostini took third place after Derek Woodman with the MZ had dropped out on the final lap.

In Assen, Redman won again, with Hailwood in second and Agostini in third. In East Germany, both Hailwood and Agostini dropped out. Redman won the race, Woodman (MZ) came in second and Havel came in third (Jawa). In Czechoslovakia, both MV Agustas dropped out again. Redman won again from Woodman. After two races without points, MV Agusta didn't enter the 350 cc race at the Ulster Grand Prix. In retrospect, this turned out to have been a major mistake as Honda did not enter either. MV Agusta didn't intend on travelling to the Finnish Grand Prix, but when Redman broke his collarbone again in Ulster, MV seized the advantage and took part. Agostini won the 350 cc race ahead of Honda's second man Bruce Beale. Honda blundered by letting Redman know that there would be no motorcycles at Monza, so he stayed in his native Rhodesia. In the end it turned out that a 350 cc Honda was ready for Redman in Monza, but it remained on the sidelines. Agostini won the race, which started dry. It rained in the final laps, causing Hailwood to fall. Just like in the 125cc class, two drivers were on 32 points before the start of the 350 cc race in Suzuka: Jim Redman and Giacomo Agostini. An exciting race for the world title was expected, but Agostini's engine started running poorly due to a broken Contact breaker spring. Hailwood took the lead and Redman was content to follow having been stung above his eye by a bee just before the start and his eye was almost closed. Second place was enough for Redman to win the world title.

1966 Mike Hailwood switched to Honda for 1966. At the season open race in the 350 cc class, the German Grand Prix at Hockenheimring, Giacomo Agostini retired and Mike Hailwood won on the Honda RC 173. In France, Hailwood won again, with Agostini 20 seconds behind. At Assen, Hailwood set a new lap record in practice, a full second faster than his own record lap from 1965 that he had set on a 500 cc MV Agusta. In the race, in conditions of rain and wind, Hailwood won with Agostini 45.2 seconds behind. In the GDR, Hailwood was entered in the 250, 350 and 500 cc classes. This would have involved riding more than 500 km in one day, which was not allowed. Hailwood had to replace the Jim Redman in the 500 cc class and, because he had won all the previous races in the 350 cc class, he dropped this class. Agostini won the race comfortably without the opposition from Honda.

A close battle between Hailwood and Agostini took place in Czechoslovakia, with Hailwood eventually coming out on top. The 350 cc race in Imatra, Finland, was won by Hailwood, while Agostini dropped out. The 350 cc Ulster Grand Prix started in the rain and Hailwood won comfortably. With this victory, Hailwood had secured his seventh world title. The Hailwood Honda did not go well during the Junior TT. At Ballacraine, 13 km into the race, he was overtaken by Agostini who started 20 seconds after him. Agostini won the race. At Monza, Hailwood didn't start and Agostini won his 3rd victory of the season.

1967 Only MV Agusta and Benelli brought full 350 cc machines into the 1967 season. Honda used the RC 174, a 250 cc six-cylinder bored to 297 cc. Hailwood won the German 350 cc Grand Prix with Giacomo Agostini almost a minute behind on his MV Agusta. After the first lap of the Junior TT, Hailwood had 48 seconds over Agostini, and by the end of the race more than three minutes lead. Hailwood won again in Assen, at the Sachsenring and at Brno securing the world title. In Ulster, Hailwood concentrated on the classes in which he was not yet a world champion, the 250 and 500 cc, and Ralph Bryans rode his six-cylinder Honda. Bryans led for five laps, but was passed by Agostini, who quickly established a lead. Now that the title had been decided in favour of Honda, the 350 cc race at Monza was more for the Italian honour for Agostini and Renzo Pasolini (Benelli). They fought a hard fight, but for second place as Ralph Bryans was already way out in front on the Honda. Agostini did not start in Japan.

1968