MV Agusta's three-cylinder racer, known within the team as the Tre, had dominated the 500 cc class from 1966 through 1972. By the 1972 season it was barely able to hold off the new generation of two-stroke machines arriving from Yamaha and Suzuki. For 1973, MV engineers bored an existing 350 cc four-cylinder unit to 433 cc as an interim measure before developing a full 500 cc version. That enlarged engine could sustain higher revs than the Tre but proved difficult to make reliable. Arturo Magni, MV's race director and chief engineer, brought in Dr. Bocchi from the Agusta helicopter division — a man who had previously worked on twelve-cylinder engines for Lamborghini and Ferrari — to continue development.
The final engine displaced 497 cc from a bore of 58 mm and a stroke of 47 mm. It produced 88 bhp at 14,000 rpm. The cylinder head was cast as a single piece with pent-roof combustion chambers; two 20.5 mm inlet valves and two 16 mm exhaust valves per cylinder were operated by bucket tappets and closed by double nested coil springs at a valve angle of 55 degrees. The camshaft, previously driven via external gears on the side of the block, was repositioned between cylinders two and three. The four-cylinder unit was 40 cm wide and weighed 55 kg dry. One persistent problem was noise: the engine measured between 125 and 130 dB(A) at the exhaust, far above a new FIM limit of 113 dB(A) introduced for 1976, and riders Read and Agostini both used earplugs during races.
The four-cylinder made its competitive debut in 1973, but reliability issues meant the older Tre was frequently used alongside it. The season was immediately complicated by internal tension: MV had signed Phil Read as a second rider to Agostini, but Read refused to accept a supporting role. Early in the season the two-stroke Yamaha TZ 500 arrived in the hands of Jarno Saarinen, who won the first two rounds. The situation changed drastically after Saarinen and Renzo Pasolini died in a collision at Monza; Yamaha withdrew for the rest of the year. With the primary two-stroke threat removed, Read pressed on with the new four-cylinder and accumulated enough points to win the world championship at the Grand Prix of Sweden. Agostini, hamstrung by an unreliable machine and team politics, finished third in the standings behind Kim Newcombe and Jack Findlay.
Agostini's departure for Yamaha — motivated by his frustration at being denied clear number-one status — left Gianfranco Bonera as Read's teammate. The four-cylinder had now matured into a clearly superior machine to the Tre, but the competitive environment had hardened: Yamaha's factory YZR 500 was updated, a flood of customer TZ 500 two-strokes filled the grids, and Barry Sheene, Paul Smart and Jack Findlay debuted the Suzuki RG 500. Despite intensive chassis development — central rear suspension, new Ceriani forks and a range of experimental rear tyres — both Read and Bonera were dissatisfied with the handling. Read nonetheless won the title at the Grand Prix of Finland, and Bonera finished second in the final standings, giving MV Agusta a dominant 1-2 in the riders' championship.
For 1975 the frame was redesigned from a demountable double-loop structure to a stiffer tubular unit, and a wider swingarm was fitted to accommodate slick rear tyres. Bonera broke a leg in pre-season testing and was replaced by Armando Toracca. Read battled through a difficult campaign against an increasingly competitive Agostini (back on Yamaha) and Suzuki. He took victories at the Belgian Grand Prix and the season finale in Czechoslovakia, but Agostini's second place in that last race gave the Italian the title — the first world 500 cc championship won on a two-stroke machine.
In 1976 Agostini returned to MV Agusta as Yamaha officially withdrew from factory competition, while Read moved to Suzuki. The machinery was supplied to the Marlboro-Api Racing Team with factory engineer support at each round. A redesigned cylinder head and exhaust mufflers were fitted to comply with the new 113 dB(A) noise regulation. The season was a disappointment: Agostini failed to reach the podium throughout the first half of the year as the Suzuki two-strokes proved clearly superior, and he turned to a Suzuki RG 500 after the second round. MV Agusta made one final appearance at the Nürburgring-Nordschleife on 29 August 1976. With lighter pistons and a lighter crankshaft fitted, Agostini won the race in difficult conditions, finishing 52 seconds clear of Marco Lucchinelli's Suzuki across seven laps. That result stands as the last 500 cc Grand Prix victory for a four-stroke engine in direct head-to-head competition with two-stroke machines.
Following the Nürburgring race, MV Agusta formally retired from motorsport after thirty years of Grand Prix competition. The new majority shareholder declined to fund continued racing development amid the company's worsening financial position. A water-cooled four-cylinder boxer with a transverse crankshaft and load-bearing engine casing was in development but never progressed beyond prototype stage. In 1978 Cagiva attempted without success to acquire the MV Agusta racers as the foundation for its own racing programme.
The MV Agusta 500 Four occupies a singular place in motorcycle racing history. It won the last four-stroke 500 cc world championship titles and scored the last GP victory for a four-stroke before the class became the exclusive domain of two-strokes until MotoGP regulations changed decades later. Its four seasons encapsulate the precise moment when the four-stroke tradition that had defined Grand Prix motorcycle racing since the sport's inception was overtaken by a new technological paradigm.