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Thread: Any last ideas before I dive into the world of custom tunes?

  1. #1
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    Aug 2016
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    Any last ideas before I dive into the world of custom tunes?

    Hello! XB12S here with a K&N and Torquehammer (originally D&D) exhaust, but no other mods. I have the dreaded XB stumble up to about 4000 RPM, most noticeable in the 2000-3500 range and at part throttle. Cruising in the city and parking lot riding are no fun at all. Full throttle operation is great, and I hear occasional misfires at idle but without any other DDFI Buells around, I don't know if that part is abnormal or if it's supposed to have a skippy idle like a Harley. I have pored over many forum threads with solutions that have worked for others that have barely changed how mine behaves.

    Any other diagnostic ideas or items I am forgetting? My next move is to get Megalogviewer HD and do some ECMDroid datalogging when the weather breaks. Thanks in advance for any help!

    See below for what has been tried without a noticeable change in behavior.

    -new intake seals
    -many TPS resets
    -Buell "race" tune
    -new plugs
    -new wires
    -breather bypass
    -subframe grounding points cleaned
    -new ground braid
    -redundant ground from subframe to coil bracket
    -D&D-specific tune from Buelltooth
    -Switch from D&D to Torquehammer exhaust (heard D&D is hard to tune for)
    -Back to Buell "race" tune
    -static timing adjustment

    All sensors appear to behave normally in ECMDroid (i.e. IAT,CLT,TPS), and AFV is always within 10% of 100. There is no obvious wiring damage. I've eliminated the fuel pump as a suspect since it performs well at full throttle, but I could be wrong in that assessment. I may have forgotten a couple of items that I checked.

  2. #2
    Senior Member
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    Jun 2018
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    TuneaBuell???????????

  3. #3
    Senior Member
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    Apr 2018
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    yugo keep us posted in what you find. I have been trying to sort the same problem on my 04 model Buell. Was able to improve idle stumble when cracking throttle open but low load/rpm cruising is still a bit jacked.

  4. #4
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    Courtenay, British Columbia, Canada
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    Search for my story How I Tuned My XB12 The Old Fashioned Way then look at the timing map. Mine was 0 degrees at idle and low rpm and throttle range which is too retarded. The bike smoothed out and started behaving when I advanced it in those areas a couple of degrees at a time.

  5. #5
    Senior Member
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    Apr 2018
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    Quote Originally Posted by mosquito View Post
    Search for my story How I Tuned My XB12 The Old Fashioned Way then look at the timing map. Mine was 0 degrees at idle and low rpm and throttle range which is too retarded. The bike smoothed out and started behaving when I advanced it in those areas a couple of degrees at a time.
    Thats how I got the idle to smooth out.

    Any way you can post your timing map?

  6. #6
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    Courtenay, British Columbia, Canada
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    my timing maps

    Here are my maps. I cannot remember which points i changed but I think they were all in the 800, 1000 and 1350 rpm's maybe 10 to 45 throttle pos. so you can see I didn't advance them much but it sure made it smoother. I'd be curious to see your timing maps before you change them.

    IMG_8019.jpgIMG_8020.jpg

  7. #7
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    Thanks everyone, I appreciate the input! I did deep-down suspect something might be ignition-related since the different tunes changed nothing about that particular behavior. I was looking at the Tuneabuell modules too but figured I'd better start small with some narrow-band datalogging and trying to get a handle on the different software packages before I spend the $. I have ECMdroid and just downloaded the trial copy of MegalogViewer HD. I think now first and foremost I'll see where my timing maps sit.

  8. #8
    Senior Member
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    Apr 2018
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    Here are my tables. Looks like I'm little bit more aggressive with idle advance. I'm actually thinking raising it up few degrees because it runs so much better.


  9. #9
    Senior Member
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    Quote Originally Posted by yugo42 View Post
    Thanks everyone, I appreciate the input! I did deep-down suspect something might be ignition-related since the different tunes changed nothing about that particular behavior. I was looking at the Tuneabuell modules too but figured I'd better start small with some narrow-band datalogging and trying to get a handle on the different software packages before I spend the $. I have ECMdroid and just downloaded the trial copy of MegalogViewer HD. I think now first and foremost I'll see where my timing maps sit.
    Crappy and stumbling idle is the reason I got on this forum too lol. I like megalog viewer, great tool and its only $40 if I remember correctly.
    I bought the parts from 14point7 to log wide band. Only had two runs with it monitoring both cylinders.

  10. #10
    Junior Member
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    Aug 2016
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    Cossack84, I forgot to mention that mine is an '04 as well! Did you do a static timing adjustment before settling on those timing table values? Did you install a second bung or get a different header to monitor both cylinders?

    I can't wait to get this thing sorted out. It's a blast to get on the throttle but that cruising/low-speed stumble really sucks the fun out of riding it, especially going around corners.



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