Yamaha FZ6R is overheating and have replaced thermostat, coolant temperature sensor, and radiator cap.Checked for leaks on all hoses and all are perfect. Burped the coolant system. Only thing I've noticed is the coolant reservoir keeps being emptied when i add coolant to it. No white smoke comes from the exhaust or burnt coolant smell. Oil is perfect. I tried a combustion leak test on the radiator and the test came back negative. Fans kick on at intended temp. Bike starts overheating when at idle. What should I do next?