The 1980's began with Kenny Roberts' feat of winning his third World GP500 championship three years in a row.
At the end of the 1970s, Yamaha had increased the muscle of its race machines with an original exhaust system device known as the "Yamaha Power Valve System" (YPVS) in order to meet the challenge of the emerging Suzuki camp that had begun to out-perform Yamaha's YZR500 in-line four with continued refinements to its rotary disc valve intake, square four machines. Then, in 1980, Yamaha introduced its first YZR500 aluminum-frame model ― the 0W48 ― and its in-line-four 0W48R featuring a reversal of the two outer cylinders. To support rider Kenny Roberts' lonely one-man stand against the rival teams, Yamaha signed Barry Sheene from Suzuki. It was ceaseless technological innovation and outstanding rider ability that enabled Yamaha to retain its GP500 throne.
In 1981, however, the balance was upset. Along with the 0W53 ―an advanced 0W48R model ― Yamaha had simultaneously introduced the square-four 0W54. However, unforeseen mechanical trouble and Roberts' poor health resulted in no-shows and the World GP 500 title was handed over to Marco Lucchinelli (Suzuki).
The era of the in-line four was already over. Thirsty for radical change and new possibilities, Yamaha went into the 1982 season with two YZR500 versions, each representing a different approach. One was an advanced version of the 0W54 ― the rotary disc valve intake, square-four 0W60. In the Argentina GP, the opening round, Roberts and Sheene promptly secured a 1-2 finish that highlighted the high level of development of the model.
The other version of the YZR500 was the 0W61, which debuted in the second round of the GP series in Salzburgring, Austria. The first 500cc machine with a V-4 engine, this was an ambitious project that featured original new experimental technologies throughout. These included a twin crankshaft power unit that reduced the frontal projected area, a newly configured frame that eliminated the under-loop section, plus a horizontally mounted suspension.
However, Roberts, who switched between the 0W60 and 0W61, depending on the needs of the race, climbed no higher than 4th in the rankings, and Graeme Crosby, who rode the 0W60 for a full season, ranked 2nd. Based on that season's results, Yamaha's determination to continue developing the 0W61 seems to have been a factor in again missing the title, though it is also a fact that the machine marked an important turning point that greatly influenced Yamaha's technological advancement after that.
Then, the following year (1983), Roberts staged a comeback on a dramatically upgraded YZR500 (0W70), featuring a refined V-4 engine mounted on a new-design aluminum Deltabox frame. Roberts dueled for the title with Freddie Spencer, who rode a NS500, the V-engine, three-cylinder model from Honda, which had switched to 2-strokes. The result was six wins for Roberts ― the same as Spencer ― three seconds, and six PPs. When that left Roberts a frustrating two points short of the title, he decided to retire from World GP racing.
After that, the YZR500 was further refined and Eddie Lawson won the championship on it three times. The formula of a 2-stroke V4 engine on an aluminum frame that Yamaha had adopted eventually became the standard for GP500 machines.