i was recently riding when i heard a loud clunk and my quad had died i let it sit for an hour and started it took awhile but i got it and there was an odd noise like a very loud and fast vibration underneath the gas tank i kinda shook it off thinking it was nothing i started to ride some more and it clunked louder and died so now i think something is really bad so i changed the starter and that wasnt it and i popped the air filter lid off and there was a fuel and oil combination could that be something? but im stumped and i have no clue please help!!!!