I have smoke coming from my exhaust, I took the plugs out one by one and found that the smoke was coming from piston 4. It is not a sweet smell, and the smoke is not black, and it does not seem like steam,I do not know if I am burning gas, oil, or coolant, does that mean I have a busted head gasket ? Is there anyway to know for sure? also, Is there anything else that can cause this problem on a bike. I know in a car I would just pull the heads and replace the gasket. Is that the same thing I need to do here?