carbon fouling plug ?

[03 ORANGE SHEE]

on my us90...
if im using the correct heat range plug
timing and points are set correctly
good hot snapping blue spark...
but i only get 20 minutes out of a new plug, it keeps carbon fouling, and gas or carb cleaner wont take if off enough to spark again

[Unclediezel]

Try one range hotter on the plug---

What does it call for -----
what are you using?---(BRAND)?

[Billy Golightly]

Something is making it run extra rich. Try cleaning the airfilter?

[MTS]

Make sure the Altituede compensation knob on the side of the carb is workin properly and is not stuck one way or the other, also i belive the olderones had a screen on the air box side of the carb, could be some crud in there, if not that the start jettin down.

[03 ORANGE SHEE]

im using a ngk dh8a.... the dh8s is the old superseded #
the airflter is perfect
mmm...:wondering never thought of that high altitude knob, ill try that now, it feels positive and working correctly

[TeamGeek6]

Yep, most likely fuel. Could try a hotter plug and see if sticking the plug nose into the chamber makes it clean up. The B8 for my 250R doesnt quite reach into the clean zone, no matter how I jet it, Ive gone to 5's or hotter, but thats *NOT* the place to start.. No engine is designed to allow a plug to foul in 20 minutes, so something is broken somewhere.