The Subaru / Robin 263-33502-H3 Exhaust Valve controls the release of exhaust gases from the engine’s combustion chamber for efficient engine performance. Designed as a replacement exhaust valve, it fits compatible Subaru/Robin small engines to provide proper sealing and exhaust flow during the combustion cycle. It works by opening to expel burnt gases and closing to maintain cylinder... https://www.wholetoolbox.com/subaru-robin-263-33502-h3-exhaust-valve