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Thread: backfire

  1. #1
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    backfire

    question, my xb9r is living again BUT im having backfires... mostly from my intake, having an occasional instant flame and gone.... new fuel in it, 93 octane.... any suggestions?

  2. #2
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    oh, stock 2007 xb9r, 6300issh on odo

  3. #3
    Senior Member Chicknstripn's Avatar
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    Check for an intake leak.
    Just google "buell xb intake leak test" and you should have all the guidance you need for the test.

    BTW does the bike have any modifications?

  4. #4
    Senior Member Silverrider's Avatar
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    OK, When you say ( my xb9r is living again) What does that mean ?

    1. Has it been dead as in parked for a long time?
    2. Have you done any work on it lately ?
    3. I know you said its Stock , completely ?
    4. at what RPM range does it back fire?

    Once you answer these questions the group with be better able to help you out.

  5. #5
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    stock as in no mods done to the engine trans or drivetrain, only have a kill switch inline for fuel pump and voltmeter to the batter. it has been sitting for about a year due to cold weather and inability to ride from military requirements.

    have drained the fuel tank today of 87 octane fuel that has been present for about 4 months. after running out remaining fuel in the line, i put about a gallon of 93 octane fuel into the tank

    chicknstrpn - would this be a good idea for having the backfire on RPMs coming down from blimping the throttle?

    tomorrow after work i plan on getting back into working the bike to figure out this issue (minor or not) but my father is thinking its from having either a firing issue or a timing issue....

  6. #6
    Senior Member Silverrider's Avatar
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    Did that old gas smell like paint thinner.? It does a number on the pre pump filter.
    How about spark plus ? You might want to take a look at them and change them.
    Last edited by Silverrider; 10-01-2017 at 11:03 PM.

  7. #7
    Senior Member Chicknstripn's Avatar
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    An intake leak can cause all sorts of idle and running problems.
    The best course of action is to check all the simple stuff first:
    Ground connections(battery terminals and headstock)
    Wires(spark plug and through out harness)
    Major connectors
    Spark plugs(if they haven't been changed fresh ones wouldn't hurt)
    Intake leak test

    None of the above should cost you anymore than some time. And hopefully will lead you to the culprit.

    Is your CEL(check engine light) coming on while riding?

    Go to www.buellmods.com and download a service manual. Should help you while taking things apart and trouble shooting.
    Good luck

  8. #8
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    silverrider - no, the old fuel smelled like fuel itself, just a bit more faint, haven't went through and taken out the fuel pump and filters yet, want to see if its something else right now, but if it persists im going to end up removing it and probably replacing the whole pump for a new one, and checking whats going on with the old one, and maybe keep it as a spare since it doesn't seem to have issues getting fuel to the injectors. going to end up also finding another set of fuel filter and sock stuff.

    sparks will be checked today as well, put new ones in when I last was able to ride my bike, and probably only have half an hour of time on the plugs but couldn't hurt putting some new ones in.

    chicknstrip - I will be running the intake leak test today and checking what I get from that. I also looked into the parts listing on this forum and I couldn't seem to find the part number for the intake seals, can you give me a quick hand with this? ground connections are good, went thru and looked at them last night. all major connectors have been disconnected, cleaned and reconnected.

    once I find my old laptop with ecmspy on it, I will figure out what its trying to throw at me as far as codes go. going to end up trying to get my hands on a service manual and a parts manual for the bike, but trying to find a hard copy from a dealer is a pain in the ass and I can only find parts catalogs online right now.

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  10. #10
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    so looking into it, havent done a intake leak test yet, but sounds like my coil pack might be going out, plugs, or plug wires going out too.... when idling, has tons of vibration and sounds like a missfire is happening. plugging into ecmspy, and testing coil firing, rear coil is noticable and front coil is almost mute... any cross references for coil packs and for plug wires? dont wish to run through harley for the coil pack but if i ha e to for the wires i guess i can....



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