what spark plug do you have?
should be a ngk b8es don't touch the gap on a new plug
should be fine out of the box
you probably have a leak somewheres making engine get extremely hot
any mods done to the quad pipe/air filter ect.
you should take carb off and clean it and check everything out
main jet size pilot jet sizecan you help me?
check fuel flow from tank to carb.
check float level ect this is something you can do right know get a can of carb cleaner.
you will need to make or buy a leak tester i believe awk08 is still selling them.
dont keep running it like that it is running lean somehow
meaning either not enough fuel or too much air.i will look for some links give me a sec
or it really is the slide not returning smoothly