MV Agusta 500 Four

MV Agusta

Company type	Private
Industry	Motorcycle manufacturing
Founded	1945 in Italy
Founder	Count Domenico Agusta
Headquarters	Varese , Italy
Products	Motorcycles
Website	www.mvagusta.com

Template:Infobox motorcycle

The MV Agusta 500 four-cylinder model, produced between 1973 and 1976, was a competition motorcycle crafted by the Italian manufacturer MV Agusta to participate in the 500 cc category, the highest division of the FIM World Motorcycle Championship. This machine secured the constructor's world title in 1973, while Phil Read clinched the riders' world championships in the 500 cc class for both 1973 and 1974.

Development and Technology

From 1966 through 1972, MV Agusta’s renowned racing bike, the three-cylinder known as the Tre, powered racer Giacomo Agostini to consecutive world titles. However, during the 1972 season, this three-cylinder engine barely maintained its edge over emerging rivals equipped with two-stroke engines from manufacturers like Yamaha and Suzuki. For the following season in 1973, MV Agusta expanded their existing 350 cc four-cylinder engine to a displacement of 433 cc, allowing it to achieve higher revolutions per minute than the three-cylinder unit. This upgraded powerplant generated approximately 88 bhp (66 kW) at an engine speed of 14,000 rpm.

Although this output was close to that of the aging Tre engine, which had reached its developmental ceiling, reliability issues plagued the smaller and lighter four-cylinder design. Arturo Magni, MV’s race manager and lead engineer, was unable to resolve these problems. Consequently, assistance was sought from Agusta’s helicopter division led by Dr. Bocchi, who had prior experience developing twelve-cylinder engines for luxury carmakers such as Lamborghini and Ferrari. Under Bocchi’s guidance, further refinement of the engine took place. The camshaft drive system was relocated; previously positioned on the side of the cylinder block, it was now situated between cylinders two and three as in earlier designs. The four-cylinder assembly measured 40 cm in width and weighed approximately 55 kg when dry. Its light alloy cylinders were cast together in a single block. The cylinder head was a one-piece casting featuring pent-roof shaped combustion chambers. Each cylinder housed two intake valves measuring 20.5 mm and two exhaust valves at 16 mm diameter. Valve actuation employed bucket tappets with double nested coil springs for closure, arranged at a valve angle of 55 degrees. The bore was enlarged to 58 mm while the stroke extended to 47 mm, resulting in a total displacement of 497 cc.

Technical specifications

MV Agusta 500 4C	1973-1974	1974	1975	1976
Valvetrain	Dual overhead camshafts (DOHC), featuring four valves per cylinder
Engine configuration	Four-stroke transversely mounted inline four-cylinder engine
Engine cooling	Air cooling
Bore	56 mm	58 mm
Stroke	44 mm	47 mm
Engine displacement	433 cc	497 cc
Lubrication system	Wet sump
Carburetors	4 × Dell'Orto carburetors, either 31 or 32 mm depending on the racing circuit
Maximum power output	80 bhp (60 kW) at 14,000 rpm	92 bhp (69 kW) at 14,000 rpm	102 bhp (76 kW) at 14,000 rpm	98 bhp (73 kW) at 14,000 rpm
Top speed	285 km/h (177 mph)		Not documented	290 km/h (180 mph)
Primary drive	Gear-driven
Clutch	Dry multi-plate clutch
Gears	6-speed transmission
Final drive	Chain drive
Frame	Double cradle frame
Front suspension	Telescopic fork suspension
Rear suspension	Swingarm with Coil springs and hydraulic shock absorbers
Brakes	Equipped with Disc brakes

1973

The four-cylinder model made its debut during the 1973 Grand Prix motorcycle racing season, but due to reliability issues, the team frequently reverted to the three-cylinder variant. Initially, the four-cylinder bike featured a single front disc brake and was fitted with spoked wheels. It ran on a 3.00-18 front tire and varied between 3.25, 3.50, or 3.75-18 rear tires depending on the track. The season proved challenging for MV Agusta and particularly for Giacomo Agostini. The team had enlisted Phil Read as a secondary rider, but Read resisted accepting a subordinate position. Additionally, the emergence of the four-cylinder two-stroke Yamaha TZ 500, piloted by Jarno Saarinen, who secured victories in the first two Grands Prix, intensified competition. Despite this, Agostini remained loyal to the three-cylinder machine; however, in the opening race he was outpaced by Read aboard the four-cylinder. At the German GP, Read claimed victory after Saarinen, Kanaya (both on Yamaha), and Agostini retired from the race. Following the tragic accident at Monza that resulted in the deaths of Saarinen and Renzo Pasolini, the 500 cc race was cancelled and Yamaha withdrew from the remainder of the season. As per prior arrangements, leading riders abstained from participating in the 1973 Isle of Man TT, making Yugoslavia the subsequent race venue. Nonetheless, a contentious decision by team manager Magni prevented MV riders from competing there due to safety concerns about the circuit—despite approval from a delegation including Agostini. At Assen's TT, Agostini retired once more while Read took first place. Agostini secured wins in Belgium and Czechoslovakia but remained behind Read in overall points and trailed riders like Kim Newcombe and Jack Findlay. Ultimately, Read clinched the world championship title at Sweden's Grand Prix after having ridden predominantly on the new four-cylinder throughout most of the season. Agostini finished third in the World Motorcycle Championship standings.

1974

Following Agostini's unexpected move to Yamaha—motivated by his belief that with Read on the team he was no longer the leading rider—Gianfranco Bonera joined Phil Read at MV Agusta. Bonera's primary responsibility, however, was to secure the Italian championship title. The four-cylinder engine had now significantly advanced compared to the earlier three-cylinder model, yet the 1974 season saw intensified competition. Yamaha introduced the updated YZR 500 factory machine, while numerous TZ 500 production racers also entered the scene. Additionally, Barry Sheene, Paul Smart, and Jack Findlay debuted the new Suzuki RG 500. With Agostini now riding for Yamaha, both Read and Bonera expressed dissatisfaction with their bike’s chassis. Various modifications were trialed, including a central rear suspension and new Ceriani front forks, along with testing a 4.50-18 rear slick tire. It is likely that no other MV Agusta racing model underwent as many adjustments during a single season.

MV Agusta withdrew from the 350cc category early in the year to concentrate efforts exclusively on the 500cc class. The opening race at the French Grand Prix marked a rare three-way competition among manufacturers, ultimately won by Phil Read after Agostini retired. The leading riders boycotted the German Grand Prix. At Assen, the front row featured machines from three different manufacturers: Yamaha (with Teuvo Länsivuori and Giacomo Agostini), MV Agusta (Phil Read), and Suzuki (Barry Sheene). Agostini claimed victory there, but in Belgium he finished second behind Read. At that event, Agostini piloted the new YZR 500, while MV Agusta had introduced a fully developed 500cc engine. Due to crashes in Sweden, both Agostini and Sheene lost their chances at the world championship. Phil Read placed second in that race but secured the world title for MV Agusta with his win at the Finnish Grand Prix. Bonera ended the season ranked second overall in the championship standings.

A new FIM regulation limiting racing motorcycle noise to 113 dB(A) posed a significant challenge for MV Agusta’s four-stroke engines. In contrast, two-stroke machines could reduce sound levels more easily without losing power by modifying their expansion chamber. The MV Agusta four-cylinder was recorded between 125 and 130 dB(A) when running with unrestricted exhausts. Both Read and Agostini resorted to wearing earplugs to cope with the intense noise levels.

1975

Despite securing the top two positions in the previous year's world championship, MV Agusta faced increasingly formidable competition. The FIM had mandated longer race distances, which required two-stroke motorcycles to either make pit stops for refueling or carry larger, heavier fuel tanks—an advantage for MV Agusta's four-stroke machines. Read expressed dissatisfaction with the handling characteristics of the four-cylinder bike. To enhance chassis rigidity, a tubular frame replaced the former demountable double loop frame. Additionally, a broader swingarm was introduced to accommodate a slick rear tire. During preseason, Gianfranco Bonera suffered a broken leg, leading to Armando Toracca stepping in as his replacement. Although Giacomo Agostini sought to reconcile with the MV team, he remained contracted to Yamaha. Toracca resented being relegated to a secondary role and compelled Read to contest for third place in the opening race, resulting in significant time losses to Agostini and Kanaya on their Yamahas. At the Austrian Grand Prix, Read finished third behind Kanaya and Länsivuori (Suzuki). The Hockenheimring favored sheer speed, enabling Read to challenge Agostini closely; however, Agostini ultimately prevailed. At Imola, Read was outmatched by Agostini, while at Assen he managed only third place. Read secured victory at Belgium’s high-speed circuit as Agostini retired along with the now-recovered Bonera and Barry Sheene. In Sweden, Read finished second behind Sheene but experienced MV’s first technical failure of the season in Finland by retiring from the race. Consequently, the championship battle remained unresolved heading into the final Grand Prix in Czechoslovakia. During that event, Agostini was forced into a refueling stop while Read won; nevertheless, Agostini’s second-place finish was sufficient to claim the world championship—marking the inaugural title for a two-stroke engine in the 500cc category.

1976

The 1976 season saw Agostini return to MV Agusta following Yamaha’s official withdrawal from competition at the end of 1975; meanwhile, Read transitioned to Suzuki after serving as MV’s lead rider. Agostini did not hold a typical factory contract; instead, MV Agustas were supplied to the "Marlboro-Api Racing Team," which received full factory engineering support throughout race events. The FIM imposed a new noise restriction of 113 dB(A), prompting modifications such as redesigned cylinder heads and mufflers on the MV machines to comply with these regulations.

MV Agusta and Agostini endured a lackluster start to the season without any podium finishes. The two-stroke Suzukis demonstrated superior performance and reliability, securing Barry Sheene’s dominance as champion. After a poor beginning, Agostini switched to riding a Suzuki RG 500 following the second race. It was only during the final race on August 29, 1976, at Germany’s Nürburgring-Nordschleife that MV Agusta reappeared with enhancements including lighter pistons and crankshaft components. Under challenging conditions, Agostini claimed victory by finishing 52 seconds ahead of second-place Marco Lucchinelli on a Suzuki after seven laps. This event marked the last time a four-stroke motorcycle won a 500cc Grand Prix when competing directly against two-stroke engines.

Exit from competition

Following the final event at the Nürburgring, MV Agusta formally ceased its participation in motorsport. After three decades of racing involvement, the newly dominant shareholder opted against allocating further funds to the racing division of the financially challenged firm. A prototype featuring a four-cylinder boxer engine with water cooling, arranged with the crankshaft mounted transversely within the frame and utilizing the engine casing as a structural component, was under development but never advanced beyond the experimental stage. In 1978, Cagiva made an unsuccessful attempt to acquire MV Agusta's racing machines to serve as a foundation for their own competition team.