Hey I have a 96 Xplorer 400 that I rebuilt the top end this spring. It has been running great until recently, I have put 2 head gaskets in it to try and stop the coolant from bubbling and shooting out the overflow.
The first time I changed the head gasket I didn't get the head machined so it started bubbling again after a few minutes after being bled.
I just had the head machined and put a new gasket in with copper spray on it aswell and it bled fine. One trip down our long driveway and back and it is already bubbling again.
Each time I bleed it I start by bleeding the 10mm screw on the head and then use a coolant funnel on the rad letting the engine warm up and running it until there are no bubbles.
My fan is working properly and comes on when hot. It does seem like a while before it comes on, not sure what is normal on these 400 2 strokes.
Right now it is bubbling so bad and it won't bleed again, air is coming out the overflow, so I suspect the head gasket might be blown again.
I drained the counterbalance oil and there isn't coolant in it, so I'm assuming it's not water pump seals, but I wouldn't know for sure.

Any help or suggestions would be greatly appreciated.

Thanks.
Jayson