Join Date: Sep 2006
Location: Southern Minnesota
If the carb is still overflowing it's not going to run properly until you fix the problem. Get a new needle valve, with a new o-ring and be done with it.
If you keep running it this way, yeah, it will take it's toll on the top end, and yes, you should change the oil once the problem is fixed. Gasoline is not a good lubricant.