Yamaha Thermostat 6CB-12411-10-00. Overview. The Yamaha 6CB-12411-10-00 Thermostat is a genuine OEM cooling system component designed to regulate engine operating temperature on Yamaha VMAX SHO outboard engines. The thermostat controls the flow of cooling water through the engine, allowing it to warm up properly and maintain the optimal temperature for efficient performance.. When functioning correctly, the thermostat opens and closes based on engine temperature to balance cooling and heat reten