59227000 Yamaha Reed Valve Kit — Gravely OEM Replacement Part59227000 Yamaha Reed Valve Kit Gravely OEM Replacement Part The 59227000 Yamaha Reed Valve Kit is a genuine Gravely OEM replacement service kit designed to restore proper reed valve function in Yamaha engines used on select Gravely zero turn mowers. Reed valves are critical in two stroke or specific engine induction systems, controlling the flow of the fuel air mixture into the combustion chamber. This kit includes the correct OEM matched reed valve