You're either running too rich or you need to switch brands of gasoline. What do the spark plugs look like? If they're black and sooty, you need to go to a leaner main jet, a lighter tension power valve spring, and/or dial the idle mixture down a bit. If the plugs are anywhere from tan to chocolate brown, switch to a brand of gasoline that's not so stinky.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!