Re: spark plug gap
Make sure you're using a good quality spark plug, like NGK.
I think they're the best. They resist fowling and last a long
long time. Your spark gap should be about .020 - .022", if
the gap is too wide it will require more current from your
CDI unit to make a hotter spark, and you may be a little too
rich on your carb needle setting if the plug looks black and sooty.
I suggest getting a new NGK plug, you can always use a spare.