The Honda 14721-ZK6-800 Exhaust Valve helps control the release of burned gases from the engine cylinder for proper combustion and efficient operation. It opens at the appropriate point in the engine cycle to allow exhaust gases to exit and closes to help maintain cylinder compression during combustion. This replacement valve is designed for compatible Honda engines and is identified ... https://www.wholetoolbox.com/honda-14721-zk6-800-exhaust-valve/14721-ZK6-800.html