F800GS Bitubo Fork Kit

Discussion in 'Parallel Universe' started by DockingPilot, Jun 1, 2009.

  1. DolphinJohn

    DolphinJohn Caveman

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    Acting up how?
  2. DockingPilot

    DockingPilot Hooked Up and Hard Over

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    If they're banging, you'll be left hanging...........
    :lol3
  3. itsatdm

    itsatdm Long timer

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    I wish one of you guys would take a set of throwaway Bitubo's apart and show pics of the innards. For those of us with a KLR mindset may be able to convert them to an open design.
  4. Gangplank

    Gangplank Advenchaintourer

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    ok, wasn't going to post this but I have a set of the stock fork innerds lying around if anyone wants to buy them from me to "see" what you can do.

    I converted my stock F800GS forks to a set of Marzocchi Shiver fork innerds. I'm happy and have a fully serviceable/revalveable fork for under $500. :-D

    Stock ones won't work on mine now anymore. Everyone who rides my bike comments on how well dialed in the front suspension is. Doesn't matter what bike they own they like it.
  5. johngil

    johngil Reseda, CA

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    I'm starting to get a pretty good clunk on topout.
    Action is still good.

    Nothing lasts forever. I've got over 10,000 miles on my Bitubo kit.
  6. Gangplank

    Gangplank Advenchaintourer

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    So they are a yearly purchase?
  7. johngil

    johngil Reseda, CA

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    They could be. I won't be buying another set, though.
  8. DockingPilot

    DockingPilot Hooked Up and Hard Over

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    Yep, their toast John.
  9. johngil

    johngil Reseda, CA

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    More or less confirmed that today.

    Out comes the check book.
  10. Indy Unlimited

    Indy Unlimited Long timer

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    Here is the latest set up (Docking Pilot's) that works great with the Traxxion Dynamics AK-20 Kit:

    Preload spacer length 225 mm
    Oil level 110 mm using 5 wt fork oil

    Springs 0.60 kg/mm x 310
    mm long
    Range of adjusters is 4.5 turns

    Cartridge valves set at C 3 R 3
    Get the new caps with compression and rebound on each fork and air bleeders.

    Spec all that when sending your forks in to Dan Anderson at Traxxion Dynamcs.

    Also Dan has been working on new fork caps to replace the modified stockers with full rebound and compression adjustments on each cap. I just spoke with him today and they made a boat load of fork caps and they are out for anodizing and will be available in 2 weeks.
  11. johngil

    johngil Reseda, CA

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    Like I said, get out the check book.
    I'll call on Monday.
    If my wife knew I was going to dump another $3K into this bike...

    Maybe then, it will be unstoppable.
  12. M N B

    M N B would rather be riding

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    Wouldn't all those numbers be weight dependent?
  13. Indy Unlimited

    Indy Unlimited Long timer

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    M N B:

    Only the spring choice needs to change.
    0.60 kg/mm is perfect for the heavier riders and/or heavy loads.
    0.55 kg/mm is better for the lighter riders and/or light loads.
    The dampening rates all have plenty of adjustment for rider preferences.
  14. Gangplank

    Gangplank Advenchaintourer

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    Are you sure that you have 225mm of preload spacer? :huh that is 8.86 inches. Sounds like a lot. Mine is 40mm = 1.5 in give or take.

    I thought these forks only had 230mm of travel.
  15. Indy Unlimited

    Indy Unlimited Long timer

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    Yeah the new AK-20 design uses a shorter spring length and longer plastic spacers to reduce unsprung weight. You still get the same full fork travel with a 310 mm long spring and great performance.
    If you pay attention to the technology everyone from motocross to Moto GP is trying to improve suspension and performance by reducing the weight of unsprung components like wheels, tires, fork tubes, springs etc.
  16. Gangplank

    Gangplank Advenchaintourer

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    I don't get it. Guess I'd have to see a diagram. :norton

    Anyway, for now I am really happy with my own fork fix. Cost me less than $500 and it is a vast improvement.
  17. M N B

    M N B would rather be riding

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    Just how heavy are we talking here?
  18. Indy Unlimited

    Indy Unlimited Long timer

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    I recommend the 0.55 kg/mm fork springs for riders up to 175 lbs.
    The rest of us over that should use 0.60 kg/mm.
    If you are real big like 300lbs I would then use 0.65kg/mm.
    The goal is to get rider & bike sag numbers (70 to 80 mm) at around 33% of the full suspension travel.
  19. Huesero

    Huesero Adventurer

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    Preload spacer length 225 mm
    Oil level 110 mm using 5 wt fork oil

    Springs 0.60 kg/mm x 310
    mm long
    Range of adjusters is 4.5 turns

    Cartridge valves set at C 3 R 3
    Get the new caps with compression and rebound on each fork and air bleeders.



    Long time, not visiting to post often here!!

    Anyway, I think I was Traxxion's first F800GS with the AK-20 kit. My fork seals went after 18k of sometimes rough riding - including the Dalton Highway to Prudhoe Bay.

    BMW actually replaced the seals and oil under warranty (!!) a few weeks ago, and put the AK-20 back in the forks without question.

    In this, Traxxion specified 7w oil, and 140mm oil level. BMW uses 7.5w, which works fine. My springs are 0.85 kg/mm from Traxxion, which are probably a tad stiff. I have compression adjustment on the left leg, and rebound on the right - you definitely want the adjustability. Good luck!
  20. Indy Unlimited

    Indy Unlimited Long timer

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    Traxxion really screwed up with the first few kits. The stock springs are 0.44 kg/mm. I use 0.95 kg/mm springs on my R1. Traxxion made them way too stiff for off road use and with too much high speed dampening on the first few BMW F800 GS kits. The set up stated above for the AK-20 kit is now proven to be very good.

    I would send your forks back with them back and get the current set up. I have used seal savers on all my off road bikes and the F800GS and no issues with fork seals for many many years. Easy to install when you get the forks off and they last many years before falling apart.