Never change your mixture to dial your quad in. Use jets to do that. Don't listen to that guy or you will be buying more than a $3 plug. Stay at 32:1 and jet it properly. Br8es plugs is what I use or. Br9es No need to go hotter than that

thanks for the quick response. That is exactly what I thought,  I'll keep jetting and checking. I've been using the Br9es. Is there anyway to measure to see if my carb is just old and worn? I know the slide has a tolerance, but is there anything else that can wear out with them? my jets are new, and I believe them to be pretty close to correct because of the way it runs, but I could be wrong.

Also another thing that concerns me with the carb is that if I leave the fuel switch to on without it running, it will leak through the overflow (I believe this is because the float height needs adjusted) could this also effect the rich fouled plug?

Thanks for the help