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Thread: Third gear clunking

  1. #1
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    Third gear clunking

    So my 05 xb12 has developed an odd clunk in third gear only. Rolling on the throttle in third it feels like a tooth is missing g on the drive belt or something. I am worried it is third gear teeth missing or effed up. Drained primary oil and it is a little shiny. But it has always been this way. Change it once a year. No chunks I thought maybe it was something in the tune. Like a weird dead spot. Reverted back to an earlier tune, same thing.

  2. #2
    Senior Member Cooter's Avatar
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    What happens if you accelerate hard in third? Does it feel worse, like it's skipping?

    Motorcycle transmissions are called constant-mesh and it would be super rare to break a gear. However, gear pairs are held together by pins in holes (dogs) that can have their edges wear off and skip like you're describing, and yes, it would only happen in one gear.

    If thats the problem and you continue to ride it, it will cause pressure on the shift fork and overheat and wreck it too.

    The only way to look at a transmission in an XB is to remove the engine and split the case.

  3. #3
    Senior Member Chicknstripn's Avatar
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    I had a similar issue with my 2007xb12r. I chased ignition timing, fuel mapping, plugs... all sorts of little “possible” things that could be the problem because I didn’t want to face the fact that third gear was toast. It was after I had a buddy ride my bike and confirm the issue was ONLY in third gear that I decided to split the cases and check it out.
    In my case I had to replace my shift forks(good idea to replace all 3 they are a wear together kind of deal), the shift dogs/gears related to 3rd gear, and the associate roller bearings. Can’t remember if I replaced the shift drum.

    Like Cooter said, only way to inspect the transmission is to split the cases. And that means you’ll need a gasket kit for an entire engine rebuild plus the case and gasket sealant necessary to do the job right. In other words, it won’t be a Saturday in the garage.

  4. #4
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    Any where you can possibly sneak a bore scope into? I recently lost first and second so thinking my fork is gone and or dogs, curious what you find out

  5. #5
    Senior Member 34nineteen's Avatar
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    This is probably what is going on. You may have rounded over dogs (or a broken one)

    https://www.hdforums.com/forum/sport...er-common.html

  6. #6
    Senior Member 34nineteen's Avatar
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    Quote Originally Posted by WILLIAMK View Post
    Any where you can possibly sneak a bore scope into? I recently lost first and second so thinking my fork is gone and or dogs, curious what you find out
    How did you lose 1st and 2nd? Can you just not shift into them? Losing both "probably" isnt a dog. I'd lean more towards a bent/damaged fork or maybe one of the springs on the shift shaft came off, or the "stop pin" wore off.


    https://www.buellxb.com/forum/showth...ting-up-to-2nd

    https://www.buellxb.com/forum/showth...tral-any-ideas
    Last edited by 34nineteen; 04-30-2019 at 10:03 PM.

  7. #7
    Senior Member Cooter's Avatar
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    Really no where you could fit a bore scope small enough to see enough detail to matter.

    It would have to be through the breather (1/4" I.d.) and hi-def enough to see a little wear on the tops of the dog pins. Unless you know a guy in the FBI with equipment like that, pull the motor and split the case.

  8. #8
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    When you roll into it hard, like drag racing it. It doesn't jump at all. Most of the time when I shift up or down I don't use the clutch other than from second to first.. Just drop the revs. Will do some more riding tomorrow m.

  9. #9
    Senior Member Chicknstripn's Avatar
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    Quote Originally Posted by lunaticfringe View Post
    Most of the time when I shift up or down I don't use the clutch other than from second to first.

    really?
    been around quite a few of you "slick shifters" thru the years and inevitably every single one eventually has a catastrophic drive-line failure......like in your case.....which is your transmission. good luck.

    I agree with lunatic on this cause and effect to a jacked up transmission. I believe clutchless shifting contributed to my third gear issue many moons ago. I wasn’t trying to be boy racer, well maybe when throwing the bike into second during a sweet wheelie. Anyway, My clutch cable also broke and I had no choice but to limp the bike home.
    When I replaced the components in my transmission the shift forks were visibly bent and worn. Also, third gear, fifth gear and the associated shift dogs had the edges worn just enough to cause third gear to “skip”.

  10. #10
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    Quote Originally Posted by 34nineteen View Post
    How did you lose 1st and 2nd? Can you just not shift into them? Losing both "probably" isnt a dog. I'd lean more towards a bent/damaged fork or maybe one of the springs on the shift shaft came off, or the "stop pin" wore off.


    https://www.buellxb.com/forum/showth...ting-up-to-2nd

    https://www.buellxb.com/forum/showth...tral-any-ideas
    I can upshift 3,4,5 but when I go down it just starts grinding/clunking never engages and you can keep trying to push it down and nothing further happens, even if you let the clutch out, no neutral light flash when going down, I think it’s a broken or bent fork, I haven’t had time to rip it open and or look at the breakdown of what gears run on what forks and or combinations of gears.



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