My 300ex hasn't run in a year i just purchased it from a family who barley used. it is backfiring very badly it has a white brothers exhaust on it also. do i just need to totally clean the carb and replace the gaskets from it sitting?
Removing the carb and cleaning it would be the first thing I'd do along with replacing the air filter. I agree with Red ^ rejetting won't be the issue chances are the carb is shelacked up from old fuel.
That's true^^^ but i think the exaust was already on it , the quad had just been sitting for a while. Old fuel will do that too especially if it has moisture in it.
But a very good and valid asumption 300.