So my brother (6) HAD to wash his own bike and while doing so he got water down the exuashst (i think the only spot). It has no filter, it does have a slight screen. It starts but bogs and almost sounds like a 2 stroke ( funky rattling noise). So how do I fix this, where going to prentice cooper TN (trail riding) in a 2 days so I NEED help please ???