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Thread: looking for updated drive belt info XB12R

  1. #11
    Senior Member Barrett's Avatar
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    Thanks a ton Bob and really appreciate the kind words. That tensioner mod you eluded to actually does relieve just enough belt tension to give the wheel bearings a break. All XR1200's from the factory have a fixed belt tensioner which is similar in design and identical in application to the XB tensioners...and only runs a few pounds of belt tension to successfully do its job. The XB tensioner is a nice design but poorly executed.
    XB TENSIONER MOD----simply elongate bottom of front hole and top of rear hole to allow pulley to slightly rotate downwards relieving a bit of belt pressure. Use common sense when enlarging the 2 bracket mounting holes.


    I've seen spring loaded tensioner pulleys for sale. Are they good in theory bad in practice?

    As in Free Spirits? As in garbage. WorldWideWeb full of hundreds of failure examples.

  2. #12
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    well thx Barrett, belt is on and it's drum tight.
    I ran it on a paddock stand for a couple of minutes and the tension loosened a little. .
    But there's no way I would leave a car timing belt this tight.
    I'm tempted to pull it again and drill out one of the tensioner holes.

    edit: @Barrett 21 turns out on the axle made all the difference, great advice thx.
    Last edited by XB Richard; 11-09-2023 at 06:55 AM.

  3. #13
    Senior Member TheWood's Avatar
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    Quote Originally Posted by XB Richard View Post
    well thx Barrett, belt is on and it's drum tight.
    I ran it on a paddock stand for a couple of minutes and the tension loosened a little. .
    But there's no way I would leave a car timing belt this tight.
    I'm tempted to pull it again and drill out one of the tensioner holes.
    To be clear; don't just drill out the holes to a larger size. Elongate(ream)the two holes precisely as Barrett laid out. Many a bearing didn't live as long as they could have due to this issue.

  4. #14
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    I think the only way I could elongate those holes is to mill them . . if I had one!
    Hacking them with a drill bit . . maybe if I just did one hole so it could still pivot squarely, hmm don't know.

  5. #15
    Senior Member TheWood's Avatar
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    Quote Originally Posted by XB Richard View Post
    I think the only way I could elongate those holes is to mill them . . if I had one!
    Hacking them with a drill bit . . maybe if I just did one hole so it could still pivot squarely, hmm don't know.
    No mill necessary. Yes, a little geometry should be used to mark the 2 shoulders you'll remove. Use the centerline(halfway between the 2 holes) as the pivot point and rotate a line from that point and the center of the hole to where it rotates approx. 2 to 3mm outside the hole. This will be the apex of your 3/8" diameter ream. As Barrrett mentioned, bottom of front hole, and top of rear hole. I understand it can be difficult to understand my layman explanation of this, but hope you get it.

    It's aluminum, not SS, so I just used a fresh 3/8" bit and VS cordless drill and took my time. Use a little thread cutting oil and pressure towards the apex. Secure in padded vise, and stay plumb and square to the face by eye(close enough if you have a good eye). Test fit, lather and repeat until you get your perfect fit to slide on the studs cleanly. If you think this is hacking then perhaps you can get a machinist to do it for you. But you should make the marks for them, otherwise he or she will fluck it up. And you may still need to return for a slight trim, unless you can leave the bike there for them to test fit. I did this in conjunction with my (3)wheel bearing and new belt replacement procedure. carpe diem!
    Last edited by TheWood; 11-11-2023 at 07:08 PM. Reason: spellcheck

  6. #16
    Senior Member Barrett's Avatar
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    ^^^^^^^^^^^^^^^^ Absolutely brilliant Bob and that is precisely how the 2 mounting holes should be slightly elongated.
    Great info.

  7. #17
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    Quote Originally Posted by miatamarty View Post
    I've seen spring loaded tensioner pulleys for sale. Are they good in theory bad in practice?
    Don't waste your money, they look cool but they fail FAST, trust me, I know

  8. #18
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    Quote Originally Posted by XB Richard View Post
    maybe if I just did one hole so it could still pivot squarely, hmm don't know.
    this is what I've done, works great

  9. #19
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    Quote Originally Posted by TheWood View Post
    No mill necessary. Yes, a little geometry should be used to mark the 2 shoulders you'll remove. Use the centerline(halfway between the 2 holes) as the pivot point and rotate a line from that point and the center of the hole to where it rotates approx. 2 to 3mm outside the hole. This will be the apex of your 3/8" diameter ream. As Barrrett mentioned, bottom of front hole, and top of rear hole. I understand it can be difficult to understand my layman explanation of this, but hope you get it.

    It's aluminum, not SS, so I just used a fresh 3/8" bit and VS cordless drill and took my time. Use a little thread cutting oil and pressure towards the apex. Secure in padded vise, and stay plumb and square to the face by eye(close enough if you have a good eye). Test fit, lather and repeat until you get your perfect fit to slide on the studs cleanly. If you think this is hacking then perhaps you can get a machinist to do it for you. But you should make the marks for them, otherwise he or she will fluck it up. And you may still need to return for a slight trim, unless you can leave the bike there for them to test fit. I did this in conjunction with my (3)wheel bearing replacement procedure. carpe diem!
    I just pivot from the top bolt, As you say, there is no need to remove that much.
    I center a 10mm rod on the lower bolt hole, then tight the 3/8 top bolt to the clamping device, then swap the rod for a mill, and by tap the part it rotates the few millimeters needed and remove that bit of metal from the bottom hole. By doing this I leave the top hole the factory dimension just slotting the lower one

  10. #20
    Senior Member TheWood's Avatar
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    Quote Originally Posted by motoqueiro View Post
    I just pivot from the top bolt, As you say, there is no need to remove that much.
    I center a 10mm rod on the lower bolt hole, then tight the 3/8 top bolt to the clamping device, then swap the rod for a mill, and by tap the part it rotates the few millimeters needed and remove that bit of metal from the bottom hole. By doing this I leave the top hole the factory dimension just slotting the lower one
    Yep, that works too. The criteria and logic behind doing both holes is to leave the maximum amount of thickness at the remaining wall. I think by only doing one, and to get the proper amount of relief you're looking for, you have to get the ream closer to the perimeter edge(weaker)than if you do both. That's my $.02



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