The 650s run a little hotter than the 500s because they don't have a mechanical fan constantly running. On a 650 the electric fan doesn't come on until you're nearly in the red on the gauge. On summer days when it's over 85 degrees F I will have the gauge nearly reach the red and the fan cycles on and off at stop lights and in heavy traffic. It should cool off back to between the bottom and middle of the thick white line when you get underway over about 35 - 40 MPH. When it's cooler, 70 degrees F and below, the temperature runs at the bottom of the thick white line but will creep up to the middle of the thick white line at extended stop light or in stop and go traffic. You will get used to the 650 using the full range of the temperature gauge. If it isn't boiling over it isn't to hot.