The Yamaha YZF-R6 is a sport bike, produced by Yamaha as a 600 class from 1999 to 2020. From 2021, production availability is limited to a non-homologated race-only specification in most global markets, causing race organizers to realign their engine eligibility criteria to encourage other manufacturers having larger than 600 cc displacements to enter road-race competition from 2022.