i have a 01 ds650, first got it it didnt have a cooling fan...went on a couple small trail rides...no over heating problems... was doing some small racing... after i finished was just creeping along it blowed a radiator hose.. (thermostat to radiator) replaced hose...had over heating problems since then...anyways checked the water pump.. the impeller was gone so was the pin... *shrugs* any other impellers work on this thing??

 

you need to get a fan on that girl! Its the low speed creeping around that gets them hot no air flow. pick one up of of ebay or one of these forums or from perma cool direct.