Question about 2003 Harley Davidson FLSTF Fat boy

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I have a 2003 Fatboy that has an unusual idle.

The exhaust seems to have a double fire only in the rear cylinder and results in a unusual sound . This occurrs only at idle. I have SE pipes with baffles in and a SE aircleaner. The HD shop installed and tuned the bike 4 years ago for the original owner 2 year s before I bought it. The bike has only 2500 miles on it and runs fine with no other issues. I have tried other plugs and wires. The pilot is 48 and I tried 45 without success. I do not see any vacuum leaks at any of the seals in the intake and the coil checks out ok

Thanks Jim

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  • Anonymous Jan 27, 2009


    cycle surgeon,

    The ignition is 100% stock HD .

    Thanks, Jim

  • jim195719711 Jan 29, 2009

    cycle surgeon,



    May be this didn't come through so I will send it again.

    the ignition is 100% HD on my 2003 fat boy. Thanks, jim

  • Dr. Mark CycleSurgeon
    Dr. Mark CycleSurgeon May 11, 2010

    What Ignition system is installed in your bike?

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  • 11 Answers

Hello Jim...
Ok, the ignition is stock...
**Have you removed the ignition cover and looked at the ignition sensor? Is resin dripping down the plate? IF so, replace the sensor, but that may or may not rectify this problem.

**YOU CAN Also remove the sensor plate and clean/inspect the pickups on the back of the sensor plate. Be sure to mark/scribe the plate prior to removal so you are back to the same timing.

**Also, check to make sure the


I also need to ask, -does your bike BACKFIRE upon Acceleration?
-does it BACKFIRE upon Deceleration?

And your idle should be set at approx. 950 rpm.

Let me know if the above has been helpful Jim...
-Marko


Posted on Jan 29, 2009

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