YZR500(0W45)

This was the representative in-line 4-cylinder, piston valve engine YZR500 that had matured through six generations from the 0W35 to the 0W53. It became the base model for the production road racer TZ500 released in 1980. The reliability of the YPVS function was optimized by "honing relief" processing that shaved the area around the exhaust port to micron-level precision. Also, the adoption of a VM carburetor that eliminated the air-side cutaway provided outstanding acceleration characteristics. In 1979, Kenny Roberts withdrew from the season opener due to injuries but returned for round two, the Austrian GP. He won five rounds that season to take his second consecutive Rider's title.

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