In a highly competitive year with a star-studded cast of unique characters including the rapidly improving Wayne Rainey, Kevin Schwantz (Suzuki), the race-hardened veteran Wayne Gardner (Honda) and Christian Sarron, Eddie Lawson returned to Yamaha after winning his second consecutive championship title and the fourth of his career. The motorcycle world watched eagerly as the stage was set for a highly competitive 1990 GP500 season.
Despite the anticipation, however, something was happening to the GP500 class. In contrast to what had been a total of close to 30 machines competing annually in this class, only 26 showed up for the qualifying of the opening round, the Japan GP. In the second round in the USA that number was down to 17, and then in Europe there were less than 20 machines competing in most rounds, including round three in Spain and the Germany and Austrian rounds. What was happening in the GP500? This was a class that had averaged about 30 machines per round in the past several years.
The reason was simple: there was a lack of machines being supplied to satellite and privateer teams. While rapid advances were being made in the latest factory machines over the past several years, development of production racers like the TZ500 was not keeping pace and they were quickly becoming obsolete. The rapid rate of advances being made in the factory machines boosted their development cost to higher and higher levels, which limited the number of machines the factories could build. This also resulted in a drop in the number of older models and engines being supplied to satellite teams and raised the price of those that were. As a consequence, privateer teams were not only becoming less competitive, they even had a hard time getting any machines at all, which forced a growing number of them to withdraw from the class altogether.
To fight this trend, Yamaha quickly decided to begin leasing out units of the previous year's YZR500 (0WC1) and individual engines. Furthermore, in the autumn of the 1990 season, Yamaha announced that it would sell ten units of the 0WC1 engine through the European constructors Harris and ROC. As a result of this measure, 23 machines, or 60% of those entered in the opening round of the 1992 season, the Japan GP, were powered by YZR500 or YZR500 engines.
Meanwhile, Wanye Rainey had emerged as the new Yamaha ace rider winning two consecutive season titles in the GP500 class in 1990 and 1991. In the 1992 season he was aiming to achieve the same feat as team manager Kenny Roberts had: a third straight GP500 title. The opening round of the season, the Japan GP, was drenched in rain, however, and still hindered by an injury to his left hand sustained in off-season testing, Rainey was only able to place 9th in the qualifying. On the second lap of the following day's race, Rainey fell after being blinded by the spray of a bike in front of him. Thus he started the season with an unexpected no-pointer.
Riding an NSR500, Mick Doohan had taken a big lead in the title race by winning the first four rounds from the opener. Rainey came back to score a win in the sixth round, the European GP, but fell again and no-pointed at the seventh round in Germany. Injuries kept him out of the next round in Holland as well. It looked at this point as if any hopes of a third straight title had vanished.
Even though it was for the noble cause of reactivating the GP500 class, Yamaha's decision to produce a large number of race engines had drained funds from its factory machine development project and prevented the team from responding quickly to new developments on the paddock. Soon there was criticism about the Yamaha team policy and rumors that Rainey was hoping to get a seat riding for some other factory.
Still, the season wasn't over yet. After racking up an impressive record of five wins and two 2nd places, Doohan crashed in the Dutch GP. Serious injury would take him out of competition for a long time. That meant Rainey's chances for the title were revived. He won two of the next four races to bring his point total to within two points of Doohan's. In the final round in South Africa, Rainey finished 3rd to claim an miraculous come-from-behind- title win.
After winning the title, Rainey commented, "It is true that during the season we were not always able to get the things we needed, and at one point I was thinking of going over to another maker. But, it is also a fact that Yamaha contributed to the GP by making a lot of engines. Even though things didn't go well this season, it was not the fault of the engineers or team on the paddock. They always gave their best, and they have promised me that next year they will build me a machine that can win. That's why I will be riding with Yamaha again next year. I am very happy now."
In the 1993 season, Yamaha once again stuck to its policy of providing production engines along with its factory effort. The result was a second Manufacturer's title in three years, as 29 riders scored points on Yamaha machines. In the GP500 class overall, the average number of entries per race was up to 33 machines.
However, a dark cloud would fall over the Yamaha camp 12th round of the 1993 season at the Misano Circuit in Italy, when Wayne Rainey high-sided coming out of the first corner on lap 10 while running in the lead and badly damaged his backbone. This injury not only took him out for the rest of the season but also ended his career as a motorcycle racer. After that, it would be a long six seasons before Yamaha won its next Manufacturer's title in 2000, and it would be 11 seasons before Yamaha had its next Rider champion in 2004.