Yamaha - Thermostat - 6FP-12411-00-00 - F90B VF90Yamaha Thermostat F90B VF90 6FP 12411 00 00 Overview The Yamaha Thermostat 6FP 12411 00 00 is one of those parts that keeps your engine running at the right temperature without you noticing ituntil somethings off. When it starts sticking or wearing out, youll see it in fluctuating temps, slow warm up, or overheating. It controls when coolant flows through the engine, so it has to open and close at the right time every time. If your motor isnt holding