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Thread: Looking for tips on identifying/ fixing an intake leak.

  1. #1
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    Looking for tips on identifying/ fixing an intake leak.

    Ok first a little info on the bike and what it is doing. 2005 xb12s with ~8300 miles. It has a drummer exhaust, kn air filter, and a race ECM that I was told was tuned for this filter/pipe configuration. The original owner provided all the receipts and dyno graphs when I purchased the bike so I'm inclined to believe him. I do not have an ECM cable yet to check or flash new tunes to the ecm.

    Recently I noticed that occasionally the bike would stumble when accelerating from a stop at a normal pace. It does not happen consistently but when it has occurred, it seems to be at roughly 2500-3000 rpm and always when the bike is still getting up to temp. Once I've been out riding for a while I have never had the stumble occur. I have also noticed some slight popping from the exhaust when decelerating and letting the engine brake.

    Both of those symptoms have me thinking I probably have a leak on the intake side. This weekend I had some time to remove the air box and do some poking around with wd-40 and I believe I have a leak on the rear intake seal. I can get a light change to the idle rpm when spraying around the rear seal. To my knowledge these seals are old enough to drive themselves now so I figure it can't hurt to replace them. Should I do any other tests before committing to replacing these seals?

    Are there any surprises I should be aware or when replacing these seals? Or any tricks to making the job easier? I have looked through the service manual and section 4.43 seems to cover removing the throttle body but past experience with other brands has taught me that sometimes the service manual doesn't give you the easiest path to getting a job done.

    Also anything else I should be on the lookout for while I'm replacing these? I plan to drop new spark plugs in at the same time and may do a compression test while I have the plugs out just for peace of mind.

  2. #2
    Senior Member 34nineteen's Avatar
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    Quote Originally Posted by Pitcherman View Post
    Ok first a little info on the bike and what it is doing. 2005 xb12s with ~8300 miles. It has a drummer exhaust, kn air filter, and a race ECM that I was told was tuned for this filter/pipe configuration. The original owner provided all the receipts and dyno graphs when I purchased the bike so I'm inclined to believe him. I do not have an ECM cable yet to check or flash new tunes to the ecm.

    Recently I noticed that occasionally the bike would stumble when accelerating from a stop at a normal pace. It does not happen consistently but when it has occurred, it seems to be at roughly 2500-3000 rpm and always when the bike is still getting up to temp. Once I've been out riding for a while I have never had the stumble occur. I have also noticed some slight popping from the exhaust when decelerating and letting the engine brake.

    Both of those symptoms have me thinking I probably have a leak on the intake side. This weekend I had some time to remove the air box and do some poking around with wd-40 and I believe I have a leak on the rear intake seal. I can get a light change to the idle rpm when spraying around the rear seal. To my knowledge these seals are old enough to drive themselves now so I figure it can't hurt to replace them. Should I do any other tests before committing to replacing these seals?

    Are there any surprises I should be aware or when replacing these seals? Or any tricks to making the job easier? I have looked through the service manual and section 4.43 seems to cover removing the throttle body but past experience with other brands has taught me that sometimes the service manual doesn't give you the easiest path to getting a job done.

    Also anything else I should be on the lookout for while I'm replacing these? I plan to drop new spark plugs in at the same time and may do a compression test while I have the plugs out just for peace of mind.
    The easiest way is to remove the frame. The shop book calls for rotating the motor, but I feel that the added work of just pulling the frame off the motor is minimal compared to the amount of access given versus a rotate.

    I've done it without rotating the motor, but its a lot of aggravating work, especially due to the very limited space available to fit a wrench (or a hand) in. I wound up cutting down some old 1/2 wrenches and 1/4" allen wrenches to get in there easier. I also picked up a long T-handle allen wrench with a ball end that I find helpful as well. There is also an offset allen wrench, sold at Harley stores that comes in handy as well. I recommend using stock Harley seals if you go this route, as the James "blue gaskets" with the lip are tricky to fit in and line up due to the limited space. There is a youtube video by NCCR that shows the weird variety of tools they use for removing/replacing the allen bolts. Some people have also used really stubby or curved 1/2" wrenchs for the size with the hex bolts. "Luckily" these tend to be easier to remove due to the hex shape that you can almost get a grip on.

    If you dont rotate the motor or pull the frame, its going to be a lot of, figuring out what tool to use to get on the bolt, turn is 1/16 of a turn, remove the tool and look for another tool to turn it another 1/16 of a turn. And after its all done, you'll probably swear that next time you're going to pull the frame.

    Its going to be at least 3 hours each way, especially the first time. RidetheLightning just did a rotate a week or so ago.



    Last edited by 34nineteen; 11-15-2021 at 04:26 PM.

  3. #3
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    When you say remove the frame instead of rotate, is this the method you're referring to?

    https://www.buellxb.com/forum/showth...your-xbr-motor

    Seems pretty straight forward.

  4. #4
    Senior Member 34nineteen's Avatar
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    Quote Originally Posted by Pitcherman View Post
    When you say remove the frame instead of rotate, is this the method you're referring to?

    https://www.buellxb.com/forum/showth...your-xbr-motor

    Seems pretty straight forward.
    Rotate = basically pitching the motor forward, pivoting on the rear mounting bolt. You lower the jack on the motor and it will rotate downwards.

    Remove = remove that rear bolt and a few more fasteners and just lift the frame right off the motor (literally). Its not as heavy as one would think, especially since you can roll it around on the fork/front wheel. The first time, I recommend getting someone to help, as its a bit clumsy and not easy to just set down on the ground. But yes, that thread is the description.

    This is one of the reasons why Harley guys dont like Buells. It takes about 30 minutes to replace a set of intake seals on a Sportster from start to finish, taking your time, and including the time to drink a celebratory beer when its done.

    The top pic is from the thread you listed, the bottom is an old one of mine. But this is what your end result would look like.





    Last edited by 34nineteen; 11-15-2021 at 05:24 PM.

  5. #5
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    Quote Originally Posted by 34nineteen View Post
    Rotate = basically pitching the motor forward, pivoting on the rear mounting bolt. You lower the jack on the motor and it will rotate downwards.

    Remove = remove that rear bolt and a few more fasteners and just lift the frame right off the motor (literally). Its not as heavy as one would think, especially since you can roll it around on the fork/front wheel. The first time, I recommend getting someone to help, as its a bit clumsy and not easy to just set down on the ground. But yes, that thread is the description.

    This is one of the reasons why Harley guys dont like Buells. It takes about 30 minutes to replace a set of intake seals on a Sportster from start to finish, taking your time, and including the time to drink a celebratory beer when its done.





    I see. I like the looks of the removal approach over rotating. Doesn't seem like much more work and will give me better access plus a chance to get to look over everything that's usually hidden.

    Am I going to need to get an ECM cable to check TPS calibration after breaking everything down this far? I plan on getting one eventually but had not yet. This is really my first dive into anything beyond regular maintenance on this particular bike.

  6. #6
    Senior Member 34nineteen's Avatar
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    Quote Originally Posted by Pitcherman View Post
    I see. I like the looks of the removal approach over rotating. Doesn't seem like much more work and will give me better access plus a chance to get to look over everything that's usually hidden.

    Am I going to need to get an ECM cable to check TPS calibration after breaking everything down this far? I plan on getting one eventually but had not yet. This is really my first dive into anything beyond regular maintenance on this particular bike.
    Yes, you will need a cable or the Buelltooth dongle to check/set TPS calibration. Which one you use is up to you. I like the simplicity of the Buelltooth setup with ECMDroid, but the "power users" will probably prefer ECMSpy and the cable.

  7. #7
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    Quote Originally Posted by 34nineteen View Post
    Yes, you will need a cable or the Buelltooth dongle to check/set TPS calibration. Which one you use is up to you. I like the simplicity of the Buelltooth setup with ECMDroid, but the "power users" will probably prefer ECMSpy and the cable.
    Understood. I'll do some more research on them to see which one is a better fit for me. No one in our house has an android phone so that could be a factor.

    Thanks for all the help.

  8. #8
    Senior Member 34nineteen's Avatar
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    Quote Originally Posted by Pitcherman View Post
    Understood. I'll do some more research on them to see which one is a better fit for me. No one in our house has an android phone so that could be a factor.

    Thanks for all the help.
    If you do some looking around, you can pick up a cheap Android phone. I did that on my last bike (project redbuell). I went to Best Buy and found a cheap Tracfone for $29. Later I realized the same phone was on sale at Target for $25, and they were having a promo for a $25 gift card, if I signed up for a Target CC.

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    All very good advise on this thread. It's can seem daunting, especially looking at the pics, but it's not really that many bolts for the engine removal and your life of intake gasket replacement will be MUCH easier because of it.
    It can be as simple as supporting the handlebars and pillion pegs with straps up to the beams for the upper section, and a paddock stand to stabilize the swingarm, with a scissor jack under the engine to lower it slowly.
    Take a close look at anything else that may need attention while its out, (looking at YOU PCV valves!) and rocker box leaks. Spark plug removal and compression test should be done first with it together.
    Good luck buddy, and take pics so you remember where everything goes

    Heres the vid that 34:19 was talking about:
    https://www.youtube.com/watch?v=UjWWUE9qrkw&t=13s

  10. #10
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    I found that a distributor clamp wrench works great on the front cylinder hex. Something like this Performance Tool W1189C SAE Offset Distributor Clamp Wrench https://www.amazon.com/dp/B000N31ZJY...ing=UTF8&psc=1



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