yz426f blown head gasket?

So I finally got my 2000 yz426f up and running. However it appears to be overheating very quickly. Coolant is spewing from the drain line and smoke is steaming out of the lower right side of the motor. The bike runs and rides pretty darn well right now....just the overheating problem. I know these bikes aren't meant to idle for more than a minute or so, but the smoking and spewing of coolant seemed a little much. After talking with a neighbor he suggested that my head gasket is possibly blown. What other signs should I look for as far as the blown gasket, and are there any other diagnoses that you guys can think of?

Does it overheat while you ride, or just when you let it idle for two minutes?

You know, I'll have to pay more attention to it tomorrow morning when I have some time. But I'm pretty sure it was just overheating while stationary. While riding it felt pretty darn good! Just freaked me out talking to a neighbor, after he looked at it for a second he thought maybe my head gasket was bad. He has a few KTM's, but I'm not sure the extent of his knowledge.

The bike won't ordinarily idle for more than one minute without venting coolant. See how it works while it's moving.

Alright, so I took the bike for a more intensive ride this morning and everything seems to be good! No overheating, and overall the bike was running really well. Once or twice though when I would shift into neutral, or pull in the clutch the motor would rev really high? Would that be because of an air leak somewhere? Or another issue?

Air leak, open hot start plunger, clogged pilot jet, or tight intake valves.

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