ksalvitelli

The gasket is leaking only when extreme demands are placed on the engine. If you checked the compression it would read normal. Like I said, I will bet you a new head gasket. You won't get to the point that it leaks so bad coolant just runs into the cylinder. As it gets worse it will spew anytime the bike is running hot or cold. After that if you are still trying to ride it around, it will put a dime size hole right through the piston when the dam finally breaks. Leaky head gaskets on stock milled heads is quite common. People always think they have cooling issues. Nope, head gasket is burnt through from a hot spot that forms at the intake side of the piston. Need more fuel baby!

I will bet you the price of a head gasket.................you've blown one. Banshees don't barf unless compression is filling up the radiator. Before you go out and do all the 'coolant tricks', pull the head off and take a look at the head gasket. It will be obvious if it is blown. You will see an area missing black gasket material between the cylinder and water jacket on the intake side of the cylinder. It will most likely be the left cylinder that is blown if not both. Milled head without bigger jetting = too lean and blow head gasket. You state that you haven't milled the head yet and your compression is 120psi. If this is true then you need to find out why you are not getting enough fuel to the pistons. I have never seen a completely stock Banshee.............overheat. They are 'bullet proof'.