overheating problems

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.

It's hard to believe that the water pump cover would leak. It has no movement and is sealed with an "O" ring. You most likely have a mechanical seal leak, the small by pass hose from the thermostat to the waterpump is leaking or the chrome water pipe is leaking. I've had leaks at all three at one time or another. The mechanical seal failed from sitting unused for many years, I somehow damaged the hose between the pump and thermostat removing and replacing my carbs and For no apparent reason the chrome water pipe "O" ring started leaking.

It sounds like the mechanical seal is leaking out the weep hole. get a flashlight and mirror and look for the weep hole under the pump housing.