Maintaining optimal engine health on your MT-15 V3 or R15 V4 is critical , and the coolant valve plays a key role. A faulty thermostat can lead to excessive heat , potentially causing serious engine damage . https://royalbikes.co.in/products/yamaha-genuine-thermostat-assembly-for-mt-15-r15-v3-v4-oem-bk6-e2410-00