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Thread: 2007 XB12R rough idle, intake backfire, bucking when speed is steady.

  1. #1
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    Exclamation 2007 XB12R rough idle, intake backfire, bucking when speed is steady.

    I have spent number of hours trying to figure out what is the problem(s).

    I have a 2007 XB12R, with stock ECM, stock open muffler (Interactive cancelled), K&N air filter and No more wire one the air box.

    The bike start and idle well when cold. But when hot, the idle start to be ****ed up, drop to stall or idle itself to 2-3K. The bike are also bucking when rolling steady, and backfiring in the intake. But when speeding the bike feel awesome, very responsive and feel like he want to fly.

    I have replace the throttle body shaft with the cnc machined one from twinmotorcycle,
    replace both intake gasket,
    new sparkplugs,
    replace the 02 sensor,
    the 2 fuel filter and the fuel pump,
    it's always fuelled with 91.

    I love this bike, but I don't know what to do next. The HD dealer near me seem pretty useless until you buy a brand new bike... So, if someone have some sort of clue for me.

    Thanks

  2. #2
    Senior Member Cooter's Avatar
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    After all the guessing and parts replacing, I hope the TPS re-set procedure was done as outlined in the Service Manual.

    http://buellmods.com/content/downloa...olt_manual.pdf
    Section 1:20, page 1-50

    Do you personally have the ability to properly use tools like ECMDroid to diagnose the bike? I can help you diagnose it, I can't help you learn to be a technician.

  3. #3
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    Yes

  4. #4
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    I guess I'm not too bad with it

  5. #5
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    I have the buelltooth with ECMdroid. And also ECMspy with the cable. I have try several time the tps reset with ECMspy and I don't think this could be the problem..

  6. #6
    Senior Member Barrett's Avatar
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    Quote Originally Posted by BlissKiller View Post
    I have spent number of hours trying to figure out what is the problem(s).

    I have a 2007 XB12R, with stock ECM, stock open muffler (Interactive cancelled), K&N air filter and No more wire one the air box.

    The bike start and idle well when cold. But when hot, the idle start to be ****ed up, drop to stall or idle itself to 2-3K. The bike are also bucking when rolling steady, and backfiring in the intake. But when speeding the bike feel awesome, very responsive and feel like he want to fly.

    I have replace the throttle body shaft with the cnc machined one from twinmotorcycle,
    replace both intake gasket,
    new sparkplugs,
    replace the 02 sensor,
    the 2 fuel filter and the fuel pump,
    it's always fuelled with 91.

    I love this bike, but I don't know what to do next. The HD dealer near me seem pretty useless until you buy a brand new bike... So, if someone have some sort of clue for me.

    Thanks
    The bike start and idle well when cold Because "cold start enrichment" mapping is masking the problem.


    But when hot, the idle start to be ****ed up, drop to stall or idle itself to 2-3K. The bike are also bucking when rolling steady, and backfiring in the intake.

    Classic lean fueling, particularly the idle speed being 3X the norm.

    You have both a vacuum leak as well as lack of fuel delivery issue. No need to bash your local dealer who lacks any desire to wrench on a 15 year old out-of-production motorcycle.

  7. #7
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    I'm not bashing on them... anyway. Ok for the vaccum leaks or fuel delivery issue. But can you give me a clue about checking this points?

  8. #8
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    @Cooter if you can help. That would be appreciated.

  9. #9
    Senior Member Cooter's Avatar
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    We're all here to help. A little fun and snark is de rigueur around here Guilty as charged.
    Barret is jumping really far ahead on diagnosis... but he's probably right anyway
    #1) Did you press the "TPS re-set" button? Or did you do the whole procedure in the manual link I gave you? READ. Everything you want me to type here is already in that.... and what your bike is doing is exactly what happens if its done wrong.
    #2) Intake leaks are found with the bike idling and spraying carb cleaner at the intake boots under the throttle body. The idle will change if theres a leak.
    #3) Checking the fuel pressure means pulling off the airbox base, disconnecting the fuel line and plugging in a gauge (49psi is spec). Find one at https://www.rev-mo.com/product-page/...ressure-tester. Note: Make SURE the TB gasket sandwiches the base on re-installation or weird running issues happen, hmmm familiar?

    Your ride is 15 years old. Common to have a fuel pump sock clogged, internal fuel line perforated, or like the filters ever been changed?? lol. Barrett has OE quality ones for sale.

    If you don't find the issue with those 3 quick checks, it's time for a proper diagnostic path. It might take longer, but it WILL find your issue, instead of jumping around hoping to get lucky.

    Start by plugging in ECMDroid and see what your AFV and EGO readings are. They are a clue to what the ECM is trying to do to compensate for whatever issue you have. Putting in a 'new tune' will never work to solve your issue.
    Last edited by Cooter; 09-12-2022 at 05:57 PM.

  10. #10
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    The TPS reset was made following the instruction in ECMspy with the cable (same as in the service manual).

    The fuel pump and the 2 filters as been change. There's no leak and the fuel pressure seems good. But not checked with gauge.

    I've already check for intake leaks with brake cleaner. Maybe I can do the test another time with carb cleaner.

    I will post pictures of the ECMspy specs soons.

    Thank you.



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