The MV Agusta 500 four-cylinder (1973–1976) was a racing motorcycle manufactured by the Italian company MV Agusta, for competing in the 500 cc series, the premier class of the FIM World Motorcycle Championship. With this motorcycle MV Agusta won the 1973 constructor's world champion and Phil Read won the 1973 and 1974 500 cc riders world championships. Development and Technology MV Agusta's famous racing machine, the three-cylinder or Tre, had powered Giacomo Agostini to the world champion every year from 1966 to 1972. In the 1972 season, the Tre was only just powerful enough to beat the newly created competition of two-stroke motorcycles from Yamaha and Suzuki. For the 1973 season, the existing 350 cc four-cylinder was bored to 433 cc, which could reach higher engine speeds than the three-cylinder. The new engine produced at 14,000 rpm. This almost matched the performance of the old Tre, which had reached the limit of its development. Arturo Magni, race director and chief engineer at MV, failed to achieve the necessary reliability with the smaller, lighter engine. The helicopter division of Agusta under Dr. Bocchi, who had previously developed twelve-cylinder engines for Lamborghini and Ferrari, was asked for help. Bocchi continued to develop the engine. The camshaft was driven via gears, previously on the side of the cylinder block, was now arranged between cylinders 2 and 3 as in the previous engines. The four-cylinder had a width of 40 cm and a dry weight of 55 kg. The light metal cylinders were cast in a single block. The one piece cast cylinder head had pent-roof shaped combustion chambers. The two inlet valves were 20.5 mm and two outlet valves 16 mm diameter. The valves were operated by bucket tappets and closed with double nested coil springs, the valve angle was 55 degrees. Bore was increased to 58 mm and stroke to 47 mm to give a 497 cc displacement. Technical data Racing history 1973 The new four-cylinder was introduced in 1973, but the machine was unreliable, so that the three-cylinder machine was often used. Initially, the four-cylinder had a single front disc and spoked wheels. A 3.00-18 front tire was used, and, depending on circuit, a 3.25, 3.50 or 3.75-18 rear tyre. It was a difficult year for MV Agusta and especially so for Giacomo Agostini. They had attracted Phil Read as "second driver", but he did not accept a supporting role. Moreover,