The golden era of motorcycle racing belonged to the 500cc premier class. From the time of its official introduction in the first World Championship in 1949 to its last race in 2001 when Valentino Rossi won the Championship with the Honda NSR500. The 500cc class has had an illustrious career. In 1965, Phil Read, Mike Hailwood, Jim Redman, Hugh Anderson, and newcomer Giacomo Agostini battled it out – with Agostini winning the crown for MV Agusta. Then in the latter half of the 1970s, it was Barry Sheene who became the last British rider to win the premier class in 1977 before Kenny Roberts became the first American rider to win in 1978 and continued doing so for three years in a row.
Though the 1950s through the 1960s were dominated by four-stroke engines, it was in the 1960s that two-strokes began to crop up in the smaller classes due to advances in engine design and technology. After the 1969 boycott by the Japanese manufacturers’ due to spiraling costs, Yamaha and Suzuki returned to racing in the early 1970s followed by Honda in 1979, heralding a new era with their two-strokers. There is no doubt that the 500cc racers were a class apart, but there are 10 that have carved a space for themselves in the hall of fame.
10 Suzuki RG500
In the 1970s, with the intention of competing in the 500cc class of GP motorcycle racing, Suzuki built the RG500 which won seven consecutive manufacturers’ titles. Designed by Makoto Hase, the RG500 was built on the successful GP racing square-four, two-stroke engine that had raced in the 1960s, the outgoing GP500 based on the road-going TR500. Suzuki’s objective was to build an engine that generated 100 horsepower, and they achieved 110. This may have been worrying from a chassis point of view as Suzuki had had issues with the XR11 750 triple that they raced in America. It made a lot of power that caused tire issues and broken chains to name a few, but thanks to their experience with the XR11, Suzuki was able to build a good chassis. At the time, the RG500 produced power between 8,000 and 10,500 rpm, nothing more, but the engineers were able to fine-tune this simply by jetting the carburetor.
Suzuki would win their first GP race in 1975 at the Assen TT, with Barry Sheene aboard the RG500, and in 1976 and 1977, Sheene would go on to win the 500cc World Championship.
9 Suzuki RGV500
The development life-cycle of Suzuki’s square-four RG500 came to an end in 1987 with the creation of a new V-formation engine which didn’t make enough power, but it would make Kevin Schwantz’s two GP wins in 1988, the first coming at the Japanese Grand Prix, all the more memorable.
The 1988 Suzuki RGV500 was slower than its Yamaha and Honda counterparts which were faster on the straights. Due to the carburetor being smack in the middle of the V, and with the crankshafts rotating in the same direction, the intake flow was impacted with the bike not making any power. Schwantz countered this by having Suzuki set it up in a way that would allow it to take advantage of other bikes in braking zones and corners, and allow him to slipstream to the front. The 1989 Pepsi-sponsored Suzuki RGV500 featured an aluminum beam chassis, first-generation Kayaba USD forks, aluminum cast calipers, and a banana-shaped swingarm. With a displacement of 499.3cc, it weighed 115 kg and was a lot quicker (170 horsepower), thanks to the updated counter-rotating crankshafts, but with a side effect – it suffered broken crankshafts due to it generating too much power.
8 MV Agusta 500 Tre
Built by Italian manufacturer MV Agusta to race in the 500cc category World Championship, the 500 Three was essentially a bored-out version of the three-cylindered MV Agusta 350cc. It had a bore and stroke of 62 mm x 55 mm, a compression ratio of 11:1, generating 78 horsepower at 12,000 rpm, and was capable of hitting a top speed of 163 mph (261 km/hr). The air-cooled engines were the first four-valve heads for MV Agusta featuring 21 mm diameter intake valves and 16.3 mm diameter exhaust valves set apart at 60º and were operated by shim buckets from a dual overhead cam system driven by a gear on the right side of the engine. The air-fuel mixture was supplied to the engine through the intake by three 27mm Dell’Orto carburetors.
Giacomo Agostini, Mike Hailwood, John Surtees, and Phil Read are some of the top names that rode the Agusta 500 racers. Of Agostini’s fifteen premier class titles, eight of these came from riding the MV Agusta 500.
7 Honda NR500
Honda withdrew from competition in 1968 when the FIM changed its rules that limited the capabilities of 500cc bikes using four cylinders as compared to the current two-strokes in the field that made more power by firing twice as much. Returning in 1977, the solution was simple – build an engine that would rev twice as fast as the current two-stroke 500s. Limited by FIM regulations, Honda built a sort of a V8 engine (in a V4 configuration) with oval pistons that had sixteen tiny valves for each bank, totaling thirty-two. During the development of the NR500, Honda was confronted with issues that ranged from connecting rods contorting at high revs (each piston had 2 connecting rods) that pulled the piston pin out of its proper orientation, to piston ring shape issues which Honda was finally able to overcome.
The best outcome the NR500 ever had was a single win at an international heat at Laguna Seca where Freddie Spencer defeated Kenny Roberts. The 1979 NR500 made approximately 100 horsepower at 16,000 rpm while the final version revved to 20,000 rpm, more than an F1 car at the time. Some may think of the NR500 as a failure, but Honda referred to it as “their teacher”.
6 Honda NS500
The NS500 was created as a replacement for the innovative, yet unsuccessful four-stroke NR500, but the bike went against Honda’s preference for four-stroke machines. The Honda Works NS500 had a two-stroke, three-cylinder V-type engine that displaced 498.6cc (166.2cc / cylinder) with a bore and stroke of 62.6mm x 54.0 mm respectively. The two rear (upward) cylinders and single (front) cylinder were angled 112º apart with a Kehin PE carburetor between them.
The early NS500 experienced piston and cylinder seizures caused by heat distortion which was solved by adding a separate sleeve inside the water jacket. With the cylinder wall plated using a German technology called Nikasil plating (chosen over hard chrome plating) that showed favorable results in tests conducted by Honda, both solutions immediately solved the seizing issues. There were 4 types of NS500s right from the prototype through early 1982 to 1983, each one having different specifications. Although behind its predecessor in terms of outright power, the NS500 outputted 123 horsepower at 11,000 rpm and a maximum torque of 58 foot-pounds at 10,500 rpm.
5 Honda NSR500
Honda’s reputation for racing performance continued to grow, when in 1985 the company debuted its NSR500, a 112º V4, water-cooled, carburetted, two-stroker, with Freddie Spencer becoming the first man to win both 250cc and 500cc championships in the same year.
Perhaps the most powerful of all the 500cc factory GP machines due to its unique single-piece crankshaft design (instead of two counter-rotating crankshafts) which reduced friction, but was bigger in width, the NSR’s design was unique with the fuel tank located under the engine and the exhaust header pipes snaking over the engine, where the tank would have been. The NSR 500 continued to get faster over the years with Japanese rider Shinichi Itoh becoming the first GP rider to hit 200 mph (320 km/hr) at Hockenheim in 1993, thanks to the introduction of fuel injection at which point the NSR500 was generating 185 horsepower. In 1994, an extra 10 horsepower was achieved through a water injection system to the exhaust that improved mid-range, and by this time the NSR weighed 286 lbs, producing 187 horsepower at 12,500 rpm. Mick Doohan would ride to victory at the World Championship with the existing engine and not the updated version, considering the bike was already difficult to handle, and reeled off another four consecutive championships.
4 Kawasaki KR500
The 494cc, water-cooled, two-stroke, 120-horsepower Kawasaki KR500 was a development of the championship-winning KR250cc rotary-valve tandem twin design, transformed into a square-4-cylinder arrangement. What set the KR500 apart from its competitors was its employment of an aluminum fuel tank that formed the frame, basically a monocoque-fuel-tank frame, with the headstock and swingarm pivot sections welded onto the hybrid frame (1981 version).
The thinking behind this was to keep the weight down for a low center of gravity and the frontal area small for high-speed aerodynamic effectiveness – courtesy of insights from Kawasaki’s aircraft division. The later version of the Kawasaki KR500 would get an external fuel tank with the engineers of the opinion that the 81 chassis was just too rigid, something racer Kork Ballington disagreed with. Regardless the chassis was revisited to provide some flex, thus deviating from the original monocoque design to a spined-backbone-styled chassis. Not as successful as the ZX-7RR and the ZX-10R, the KR500 did however find top riders aboard it – Eddie Lawson, Kork Ballington, and Greg Hansford.
3 Honda Elf 2
Elf’s entry into Grand Prix racing may have begun with them selling patented swingarms to Honda, but it was more their development of an experimental GP bike that got the wheels turning with Honda supplying ELF with 1000 RSC endurance engines for the 1980 season – the result was the ELFe, with “e” meaning endurance. ELF would compete in every race until 1983, placing third in the final 1000cc TT/Endurance race at Mugello in 1983.
Their 1000cc endurance racing enabled them to graduate to GP racing in 1984 with Honda supporting them with RS500 engines. The bike was the ELF2 that looked like a mini-streamliner from afar and was also known as the “Black Bird”. It featured an experimental steering system where the handlebars mounted to a cross member and were rigged to move fore and aft instead of pivoting side to side. Powered by a 500cc, two-stroke, water-cooled, 8-valve, v-twin engine that made 130 horsepower, the ELF2 didn’t debut until the next year at Le Mans by which time a new version of the ELF, the ELF2A made its introduction.
2 Aprilia RSW-2
The Aprilia RSW-2 made its racing debut in the 500cc class which was a larger off-shoot of its sibling, the RSV 250, that the Noale team raced in the 250cc class. With an initial displacement of 410cc in 1994, Aprilia raised the capacity to 430cc in 1996 and then 460cc by the middle of the ’97 season. In 1998, they were absent from competition, developing a brand new 498cc motor.
In theory, the Aprilia RSW-2s were able to lap faster, but the heavier fours had a 60-plus horsepower advantage, which meant greater acceleration for them with the twins being unable to use their cornering speed to overtake them. By 2000, Aprilia had the RAVE valve in place to electronically manage the exhaust, 42 mm upside-down Öhlins front forks, APS progressive system with an Öhlins shock absorber, a carbon fiber swingarm, and the last manufactured models got injectors for indirect injection. Weighing in dry at 110kg with a bore and stroke of 72.8 mm x 60.0 mm, the agile RSW-2 500 was not very successful, making 140 horsepower at 11,500 rpm compared to the fours that made 200 horsepower. In the 7 years the Aprilia RSW-2 ran, it only managed 5 podiums.
1 Yamaha YZR500
The YZR500 doesn’t need an introduction. Its illustrious career has seen the likes of Giacomo Agostini and Eddie Lawson win the World Championship. Following in their footsteps in 1991, Wayne Rainey would score a World Championship win aboard the Yamaha “0WC1” YZR500 winning seven races, the first of more to come.
The World Championship regulations changed in 1991 requiring GP500 machines to weigh a minimum of 286 lbs. In the same year, Yamaha adopted an electronic control suspension developed in partnership with Öhlins where the sensor-based electrical system measures suspension stroke by analyzing the data and sending it back to the suspension, changing its behavior on the fly – the system could also be manipulated via buttons on the handlebar. Wayne Rainey’s second championship came on the YZR500 0WD3 which produced 155 horsepower. In 1992, Yamaha found a little more horsepower for the 0WE0 version, upping it to 160 while later in the season the engineers changed the ignition sequence that helped improve power delivery and acceleration. Rainey would win a third championship that year on the 0WE0 YZR500. For 30 years, from 1972 until 2002, Yamaha won 115 races that included 11 World Championships and 9 Constructors titles on the YZR500.
Source
https://www.topspeed.com/best-500cc-motogp-bikes-ever/
