I recently rebuilt the top end on my 1997 king quad 300. I put in new rings and gaskets. it runs great accept there is a loud popping sound coming from the top end at high rpm. I was looking at it and it looks like it has a blown head gasket.it is leaking oil and it is smoking on one side. I was wondering if the head gasket is blown and if it is, what would most likley cause it?