ATHENA offers these replacement piston rings for the ATHENA P400485100050 81mm kit mounted on YAMAHA YZF, YZ-F 250cc 4 stroke motocross from 2014 to 2017 and YAMAHA WR-F, WRF 250cc 4 stroke from 2015 to 2017. This includes the complete set of piston rings with 2 compression rings, protection rings and oil wiper. We recommend changing the piston rings every 20 hours or 8,000 km to avoid any loss of compression. As a reminder, it is preferable to also change the seals when reassembling your cylinder on your engine to ensure a perfect seal.