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Thread: Sputter/hesitation at idle...hesitation low RPM

  1. #1
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    Sputter/hesitation at idle...hesitation low RPM

    I just got an XB12R 2008.
    It is not running right...see video.
    Any idea what might be wrong?
    https://www.dropbox.com/s/3ld6uyl3v5..._1883.MOV?dl=0
    jared

  2. #2
    Senior Member Cooter's Avatar
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    You have intermittent spark on one cylinder.

    Possible causes:
    1) Most common... Bad/fouled plug (Buellizm #54 Repeated cold starts without warming it up WILL do that)
    2) Bad or poorly connected plug wire
    3) Bad coil
    4) Primary wiring to the coil is compromised

    Possible repairs:
    1) Clean or replace the plugs NGK Iridium work well either DCPR8EIX or the 'colder' DCPR9EIX.
    2) Check or replace the plug wires for $22:https://st-paul-harley-davidson-buel...710051e0&_ss=r
    3) Replace the coil for $42: https://st-paul-harley-davidson-buel...6cc8acb5&_ss=r
    4) Check 12V spark signal at the coil terminals #1 and #3
    Last edited by Cooter; 09-25-2020 at 05:56 PM.

  3. #3
    Senior Member Barrett's Avatar
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    ya know Shaughn, when you're not being tormented and ridiculed by resident interloper Aaron...you provide some wonderfully accurate, concise info. i'll be lying in waiting for retaliatory response by him, so don't feel singled out.

    Sir:is this the firebolt that came out of New Hampshire? if so, from Concord north they're notorious for having putrid gasoline at many of their retail outlets. and if it was recently offered for sale, chances are great that it had been cold start/short run times on many occasions, likely fouling the plugs and diluting the motor oil. CHANGE BOTH!
    1-like Shaughn mentioned...NGK DCPR8EIX a great choice and stock heat range...9EIX one range colder. change them and do NOT gap them. simply add a small dab of anti-seize to each plug thread, and check the gap by folding over the cover of a pack of matches doubling itself in thickness....and see if it fits in the factory gap. if so it's close enough and will not harm the electrode or dollop of iridium placed on inside of ground electrode during production.
    2-contrary to the service manual, you do NOT have to move the motor whatsoever to change plugs and wires. if tackling this task then ask and i'll walk you thru it. a few common tools and some tenderness and patience required.
    3-go to the left rear frame spar. you'll see the fuel pump located there. on the pump housing is a 13mm hex head bolt. it is the fuel drain plug with O-ring. remove and drain the crap fuel. if the O-ring needs replacing let me know and i'll send you one. then fill the tank with either 100LL Av-Gas if you can find it locally....or the best sunoco premium you can find along with either a fuel treatment such as SeaFoam...or injector cleaner/fuel treatment. use quality. once filled give the bike a good 1/2 hour ride to let the fuel and treatment mixture circulate.

  4. #4
    Senior Member Cooter's Avatar
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    Go light on the ll100 aviation fuel the octane rating is not computed using the same formula as automotive use it works out to about 114 octane and LL stands for low lead but the lead content in av fuel is several times higher than the highest amount in auto fuel from the 70ís it will kill most O2 sensors on the first tank. If you have a local airport you can get fuel at 60% unleaded super and 40% 100 octane unleaded av gas should give about 105 to 110 octane and good cleaning additives.

  6. #6
    Senior Member Cooter's Avatar
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    I didn't know that about the "LL" part of aviation gas but cvc is right. Any lead will kill your O2 Maybe a better choice is boat gas for no Ethanol?

    But any octane higher than the number recommended for the engine will be fine. It is simply a measure of "knock resistance". It's not going to blow anything up and doesn't contain more magic horsepowers. In FACT, higher octane fuel burns slower and more evenly.

    If you're just looking for the cleaning feature of good gas, just add gas cleaners. Seafoam FTW!!

    Either way please report up on this thread when you get her running again

  7. #7
    Senior Member 34nineteen's Avatar
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    Quote Originally Posted by Cooter
    3) Replace the coil for $42
    Important!!!

    If you choose to go this route, be sure to mark one of the coils with a large “x” so you don’t mix them up!!!

  8. #8
    Senior Member Cooter's Avatar
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    Like REALLY large, In fact, you should write "NO! This is the BAAAADDDD OONNNEEEE, do NOT re-install it again!!" In the largest neon paint you can find.

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    I think I am the one who Barrett might have been referring to with a bike from New Hampshire. I have a 2008 buell firebolt that was, well is running rough/coughs from time to time. Almost identical to what the original post said. Odd. However, My airbox top is missing. I assumed my bike was running too lean. I haven’t had a chance to do Everything to it that cooter suggested earlier. I’m working on getting the parts and my buelltooth is coming in Friday so I can check my codes. Never really thought to change/replace my plugs because it only has 11,000 miles in it but you all mention it like it could be common. Mine is not running as rough as this as jcombs posted video at all. It’s smooth for the most part just kind of coughs from time to time like the fuel mixture isn’t correct.

  10. #10
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    I am going to replace my plugs just to eliminate that issue. Barrett you mentioned a process to change them. Can you help me with this process by giving me some pointers? You mentioned possibly some certain tools?



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