Hi. I have a 94 flstn with a 1340 evo running a super e carb and true dual exhaust. The bike is running like crap! Backfiring sputtering, rough idle. I pulled the plug from the front cylinder and it was black as nite but dry. Also stuck my finger in the pipe and it came out black. Any ideas? I just got the tins back from a repaint and it was running fine before, put the tins back on and it is burping and slurping. Could it be as easy as a fouled plug. Maybe it was bad before and I just didn't know it......

 

Anybody? Could use some help here

 

Fouled plug can certainly do that. If you have a spare set it would be an easy check. You say they are black but dry. I have fouled mine before and they were dry. Would check that first. Also could have gotten crap down in the carb bowl due to junk getting in the tank. But if it is running that rough it sounds just like a fouled plug. Basically missing so bad you could drop the bike in a turn.

 

Yeah. I'm gonna change the plugs tomorrow. Hopefully that fixes the issue. I wonder what fouled them though. I wonder if I'm choking the bike too much. Will that foul the plugs up? But is only the front one and not both. So I don't know

 

Absolutely. Using the choke too much will certainly foul the plugs. An S&S carb dumps a lot of fuel with its enricher and can cause that. My carb set up runs perfect BUT with my changes I cannot run my choke much at all. I will use it to simply get the bike started and then use the throttle lock to warm it up.

 

Once plugs are fouled they're not no good anymore. Usually once you lean up the mixture and and burn it off, they're fine. But plugs are so cheap, don't chance it, you gotta start with the small stuff.

 

So that was it! New plugs and she runs like a top! Now I just have to remember not to lean on my enricher and all will be well

 

Glad to hear it was a simple fix. I was going to chime in with the air cleaner plugged up, enricher valve stuck, ignition wiring. etc. etc.

 

Nice to hear that's all it was.
I learned from troubleshooting in the electrical trade to always look for the little stuff, because it almost always is something little...

 

If it happens again you my be running to rich even if your not using the enricher as much. Put a few miles on the new plugs, then pull them and see if they're black ( rich), white ( lean), tan (perfect). Then adjust your mixture screw accordingly.