Yamaha forks on a BMW F650GS Dakar

Discussion in 'Thumpers' started by skibum_1260, Oct 23, 2008.

  1. Aquatic

    Aquatic Long timer

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  2. LoJack

    LoJack Long timer

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    You were nice enough to send me that a number of months ago. I still have it. I have been learning Solid Works and have been wanting to draw it in there. I need to get a better computer, though. My laptop blows for SW. I've been looking at towers but am not sure yet about a graphics card.

    A year or so ago a friend that works with SW was helping me model a swing arm that had arms fully machined out of billet that had a lattice structure for strength. It was wicked cool looking but I realized it would cost about a grand to have the arms machined. That, and the more I learned about aluminum, the less I realized I knew. That's partly what prompted me to go back to school.
  3. dwayne

    dwayne Silly Adventurer

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    With regards to the cush drive I agree completely. Especially for a bike that is ridden on pavement where there isn't a lot of wheel spin/slip. Having said that KTM cush drives wheels will bolt on to KTM non cush drive bikes without modification. KTM cush drives are a fair bit lighter than BMW cush drives.

    With regards to the axle, the same axle supports the 950 adventure, a heavier more powerful bike. Yes it is lighter, but it is also larger in diameter (by a lot). Increases in diameter significantly increase strength compared to changes in wall thickness, plus you get a larger bearing surface.

    Unsprung weight plays a much larger role in performance than sprung weight, rotational mass more again. Saving even a pound in the wheels might just translate into a significant handling difference if you're the type of rider that can push the bike to the limit.

    Then there is the issue of tire selection for an 18" wheel. You have waaaay more dirt applications available, but I am not so sure about DOT applications.

    Is it worth the effort and money...I doubt it.
  4. dwayne

    dwayne Silly Adventurer

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    You use a thinner section when using steel, looks can be deceiving. Aluminum's strength to weight ratio is better than steel, but it strength to thickness ratio is shockingly poor compared to steel. You would also change the feel of the rear suspension, steel has more flex...I imagine there would be both good and bad things that come from a more rigid swingarm.

    Again the KTM 950/990 would be a decent comparison for weight and use to a Dakar.

    I suspect you wouldn't break most swingarms from modern bikes, but I can only imagine the headaches of trying to modify one (remember the bmw chain is on the "wrong" side). Take a look at which parts get modded (or not) on a tourtech rally bike as a baseline the for value of a high performance mod. I believe they use the stock swing arm.
  5. Gangplank

    Gangplank Advenchaintourer

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    For guys using the YZ250F or 450F front end set up and tripples with dirt bike or fat bars do you still need or want bar risers or is the stock height good enough?
  6. kubiak

    kubiak Long timer

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    i still run bar risers on mine. i like them high and so i can slide the yz fork tubes up in the triple clamps.
  7. Aquatic

    Aquatic Long timer

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    I'll save a bit of trouble if you ask nicely :evil

    You still got it lying around somewhere?:ear
  8. LoJack

    LoJack Long timer

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    I don't have the SW part file, just a .PDF. If I can get it, how about an even trade.:freaky
  9. WayneC

    WayneC Long timer

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    Ah fair trade is a wonderful thing, you want an honest broker ? my fees are reasonable :rofl
  10. swamp

    swamp U lie&yo'breff stank

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    thanks again sir :nod
  11. swamp

    swamp U lie&yo'breff stank

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    pretty sure some of the husqvarna 2 strokes also have the chain on the wrong side. just an idea.
  12. Gangplank

    Gangplank Advenchaintourer

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    What is the story with the dust cover? If I'm using YZ250F and using the YZ bearings to & bottom right? So do I use the BMW dust cover or YZ?


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  13. WayneC

    WayneC Long timer

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    If you are referring to the steering head bearings, look to the Koyo bearings with inbuilt seal, one is
    Koyo Part No 320/28JRRS (Replacement for stock BMW bearing)
    F800 and other model owners have moved to them for longer SHB life, I would still use the metal dust cover as well
  14. Gangplank

    Gangplank Advenchaintourer

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    The bearings on the steering stem. Thanks for the link. Planning to get a replacement set of bearings for the YZ.

    What I'm really asking are what dust covers are used?
  15. tomatoe333

    tomatoe333 Long timer

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    I used a KTM dust cover on the top side. Same part number used on pretty much every KTM since 2000. Works nicely.

    Bottom just gets the seal included in the bearing kit.
  16. isgila

    isgila Been here awhile

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    Good day, this topic have been discuss before few pages back, yes i read the whole thread..:cry
    I believe Herrhelmet and Rcmad made 12 sets of links to raise the rear to match the yz front. And yes I do agree that this is not the best way to go but sending the forks to HoH or getting a customise hyperpro not for someone who lives outside of USA. I was reading the orange crush forum and got to know that emigracing.com does customise links for ktms. If anybody would be so kind to share the CAD drawings with me, i will check out the cost to run a couple of sets..
    Thank you.
  17. Gangplank

    Gangplank Advenchaintourer

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    Does anyone have measurements for the ignition key lock mount? I remember seeing a drawing around here but can't find it now.

    Thanks,



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  18. GSBS

    GSBS FunHog

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    Scroll about 2/3 of the way down in this document.
  19. swamp

    swamp U lie&yo'breff stank

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    quick question.
    will the center stand work with the 18" rear wheel?

    ::edit::

    never mind

    [​IMG]
  20. Gangplank

    Gangplank Advenchaintourer

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    Anyone have measurements for the Dakar center stand and side stand? I may need to extend-a-weld a GS stand to make it dakar'd