Motorcycle Repair: fowling plugs and back fires, stock carb, short trips

Question
QUESTION: mike,i have a 1980 sportster 1000 bored to a 1340. i fowl plugs all the time even on short trips ( 1 - 3 miles ). it always back fires . i have strate pipes on and a s&s carb. how would i aproach the problem? thanks mike

ANSWER: Has it always done this since you bored it?
Mike

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QUESTION: mike, i'm not sure. i bought the bike last year and before that it sat for 2 years. a freind told me it could be the s&s carb. he says they are junk . should i put the original carb back on ?

Answer
Start by doing a OHMs test ont he coil and plug wires. If they are ok, then I would rejett the carb. the jetting might be to large, which would cause you to foul plugs. The S&S carb is going to work alot bettr than the stock carb.
Good luck and happy riding
Mike