i got a 99 sportster xl1200c with an s&s carb and it keeps fouling plugs. Even when i have the bike at an idle to adjust the carb it fouls the plugs. When giving it gas at about half throttle the bike cuts out, misfires, and backfires. It had bad gas in it all winter and was run with thatgas, but icleaned out the carb and the lines. Any idea what this could be?(i know its running rich but i cant seem to get it right).
Also, what is the recommended heat range and gap for the spark plugs on this bike, and what kind of plugs are you guys running?

Thanks for the feedback!

 

I assume you mean it's gas fouling and not oil fouling? Could be you've got a float level that's too high or a sticking float valve. Gas turns pretty gummy when it gets old. I'd pull the carb out and apart - or at least drop the bowl - and do a visual inspection and ensure the float is working ok. Also, if the float is sunken (usually perforated and filling with fuel) it won't raise up and close the valve. In any event, it sounds to me like a float issue, regardless of the specific cause.

 

+1 I run $2 Champion RA8HC plugs gapped at .040, they are the correct crossreferenced plug for the stock HD plug.

 

I had issues with moine fouling out too. I switched plugs, front to back and back to front and it RAN 100% I am guessing the gap in my plugs is off. I am about to get new plugs and gap them correctly. I never checked the gap on the first install