I am new to this site, I have recently purchased bikes for my boy and myself.....its been 10 years since I owned a bike. The last was a 97 CR500 which was god awful fast and a ton of fun to ride.....my wife wears that bike on her finger too this day! Anyhow back to my question I recently picked up an 01 XR650 that is in beautiful shape and ran well when I looked it over and test rode it. The bike has sat for quite some time and hasn't been ridden. Today I started the bike up and let it idle in the garage for about 10-15 minutes while I looked for a test light (the person I bought it from had an after market tailight turn signal set up on the bike and I removed this and I plan to reconnect the factory tailight) As I was doing this the bike started puking antifreeze on the floor and I could hear the fluid boiling....I stopped the bike immediately. I have ordered a shop manual for the bike so I have some idea what the heck I am dealing with, I dont have it yet. I grew up with two strokes and dont have a clue about the 4 strokes so its learn as I go. Could this be a bad thermostat (sticking), Can anyone explain to me how this thermostat works? Or could it be a water pump? I appreciate the help Best, Paws