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Thread: XB9 runs like **** when hot

  1. #1
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    XB9 runs like **** when hot

    Hi guys, back with another problem...

    I'm being a bit lazy and asking for help rather than properly trying to diagnose the problem myself due to a split disc in my back which means I can only work on the bike for limited time. Anyway, enough of my bs sob story...

    The bike runs fine when cold but once up to temp it idles really ****, like it's trying to die slowly, then it will just run on one cylinder on and off. This is only when idle or really low revs riding. So it kinda hesitates when revving from idle, like when your carbs are badly set up badly (I know it's injection though). Also get some pretty gnarly backfires and also some through the airbox (what's this called?). As soon as the revs are a bit higher the bike seems totally fine, never any hesitation when giving it more throttle when riding.

    I tried raising the idle speed a bit but it just means it runs really high most the time but would still go to one cylinder when hot and idling anyway. I have the buelltooth diagnostic tool (which I'm not really sure what I'm doing with) but that brought up no codes. Has a Jardine exhaust, K&N air filter which looks pretty clean (only had the bike a few months). I bought some new spark plugs so will change these this week. What else would you guys be looking at?

    Thanks for any input.

    Owen

  2. #2
    Senior Member Cooter's Avatar
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    Use the Buelltooth you have to send wireless data to the free ECMDroid program and look up the AFV. Instructions are on there site. That will tell you if it is running rich or lean and a good start to diagnosis.


    Or just blindly buy a battery, fuel pump, and intake seals... that should do it

  3. #3
    +1 on buelltooth. Mine was never as severe as yours, but PO put K&N, inner airbox delete, and jardine on and it felt hot, and idled poorly on hot starts after re-fills. AFV was showing lean, so I re-mapped with jardine map from buelltooth and runs amazing now. Feels smoother, no hesitation at low speed, runs cooler, and no more idle issues. maybe I just got lucky...

  4. #4
    Senior Member squidbuellie's Avatar
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    Here is some food for thought.
    Depending on the one you have they will always have a air leak either on the rivets on the can or the rear cap..
    They use a sub par muffler packing that usually comes apart in about 3-4,000 miles

    So with that in mine the decel pops or back fires is your bike sucking cold air I have even seen the elbow at the header leak

    you can change the plugs and it might be the problem depending on how many miles you have
    I have also seen bad tps and have even seen bad cam position sensor behave that way

  5. #5
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    Thanks for the info guys. Will have a look at the Buelltooth and change the plugs. Also, the exhaust is pretty banged up so I bet it does have some air leaks. The popping on decel doesn't bother me (I quite like it) but the running on 1 cylinder is a pain in the ass.

    Cheers

  6. #6
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    So I looked on the Buelltooth site and they have the following maps for the XB9:

    Buell Race Kit
    ​D&D
    ​Buelltooth Exhaust System (Specify Model Purchased)

    I have the jardine exhaust on mine, anyone fancy taking a stab in the dark at which map would be the closest one?

    Cheers

  7. #7
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    You should check the intake seals since it's easy to do.

  8. #8
    Senior Member squidbuellie's Avatar
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    Neither map is a good fit for you. They both have a controlled exhaust flow so over time the pipe does not change. Your jardean will be all over the place and even new does not have the same back pressure.

    If you can find a map for a hawk or drummer that would probably work better for you.
    You might want to just check it with ecmspy. You might even have a clogged injector.... but with out the bike in front of me I’m just spit balling it.

  9. #9
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    Quote Originally Posted by njloco View Post
    You should check the intake seals since it's easy to do.
    I agree with this guy. Its a cheap and easy check. You may also want to reverse the plug wires and inspect the plugs to make sure its not a fouling plug or faulty wire.

    It could be what the other guys said as well, but I'd start here. All the Seafoam and Race tunes in the world can't fix a leaky intake seal... and odds are that your seals are probably original and about 10-15 years old. The design isnt necessarily the most robust either.

    Replacing them is somewhat of a bear, especially if you are having back issues. Its not really that hard, but the weird angles you have to position yourself in to get to the bolts is time consuming and requires small double jointed fingers and elbows. I wound up cutting down a cheap set of Harbor Freight tools and has to work at them 1/16th of a turn at a time.
    Last edited by 34nineteen; 11-14-2019 at 11:17 PM.

  10. #10
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    Cheers for all the info and advice. I'll start checking all those things, it got much worse on the way home, actually running on one cylinder while riding with higher revs and loads of backfiring so maybe plugs are fouling? I'll change em.
    As for the intake seals, prob are the origonal as the bike has been badly neglected, they rarely come up for sale in Hong Kong so I'd have bought it even if it was in bits!!!

    Seems people don't have much love for the Jardine exhaust, so I might consider changing that to one that Buelltooth supply with a map, although quite a bit of money - plus I have another project bike causing me headache and expense. Love em both!



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