Originally Posted by focallength
....I have to check the oil and water pump and inspect bearings.....
I was helping a friend with a DRZ that had a chronic overheating problem. Repeated blown headgaskets, warped head, etc. It turned out that the waterpump impeller had unglued itself from the shaft and would turn on the shaft with only a little resistance. Or, not turn when the bike was running. It looked good, though.
Doesn't sound like your problem, but it's easy to check when you're in there.