LC4 fork oil level?

Discussion in 'Thumpers' started by DRZmaui, Sep 10, 2006.

  1. DRZmaui

    DRZmaui Been here awhile

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    Getting ready to update the suspension on my 03’ 640 Adv. The White Power manual is a bit unclear. It mentions that the fork oil should be 25mm under the 4 holes of the inner damper.
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    My question is this, what level (and oil wt.) has work for others. My weight is 195pds, and I’m installing .50 fork springs.
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    Additionally, I would like to thank Creeper for all the time and advice he given to this tread. I’m been of great help understanding the intricacies of this amazing machine.
    #1
  2. creeper

    creeper Still alive...

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    This first bit is just to ensure that you have an adequate volume of oil to start with.

    [​IMG]

    This next bit is the operating range. More air space equals a softer rate of pressure rise with a lighter final pressure for a given travel. Less air space equals a faster rise with a higher final pressure.

    The starting point, regardless of chamber volume is 14.7 psi... unless you haven't bled your forks lately, or bled them when compressed.

    120mm is the "standard" oil level... but, to my knowledge, you can go from 110mm to 150mm to fine tune the air chamber on the 4860 MXMAs.

    [​IMG]

    Going with a firmer spring for your weight is a good idea. The stock 44/46 springs are kinda soft for fast off-road work or an MX track (:huh)... great for tight, slow technical stuff, but you'll use up travel fast when the going gets rough and quick.

    On that last bit, your welcome... my pleasure.

    C
    #2
  3. DRZmaui

    DRZmaui Been here awhile

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    Thanks for taking the time to help. I’m presently preparing my LC4 for a around the world trip next year. Your willingness to share your extensive knowledge has been of great help ‘setting up’ my bike. Keep up the good work!
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  4. slideways

    slideways permanent ex-pat

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    The only change I would make would be the fork oil. The manual recommends 5wt fork oil, I have found the best substitute for fork oil is Mobil1 synthetic ATF.
    #4
  5. PackMule

    PackMule love what you do Super Moderator

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    FYI -- the Mobil1 is measured at 7.5wt. I've used it in my VFR for the past several cycles to good effect. It'll be going in the RXC soon -- though the marzocci's call for 7.5wt where the WP's spec 5wt. YMMV.
    #5
  6. Zerodog

    Zerodog Long timer

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    Get 5wt fork oil. Heavier oil will most likely result in compression spikes. KTMs have a hard time flowing enough oil as it is, nevermind adding thicker oil. Oil height depends a lot on what you are riding. But it is easier to start low and add more. 5ccs=about 5mm in height. It isn't perfect but it is close enough to dial it in. If you want a softer ride on small stuff go with a lower level. Start at 140 and see how it feels. Put a zip tye on your fork leg to see how far your fork is moving to judge if you are even using all of your travel. If you are bottoming out easy add more oil or compression until you don't. If you want to firm up the ride on the road or you jump a lot go with a higher level. Start at 120mm.
    #6
  7. meat popsicle

    meat popsicle Ignostic

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    "ca 420 ccm" = capacity of 420 cubic centimeters which is also 420 milliliters... am I missing something? :scratch

    I just put 473 ml into one leg and I can't even see oil outside the inner fork leg, much less measure 150 mm.
    #7
  8. dirty_sanchez

    dirty_sanchez Dirty_Sanchez

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    I changed the fork oil in my bike a few months back.

    For fun I measured right at 435cc out of each leg when I dumped the old oil.

    450cc's went in to start-no real difference in feeling.

    With the forks mounted back up, I discovered an empty Magura blood bottle, filled it with another 50cc's and used the tiny dispense tip to add another bit of oil.

    500cc's of 5wt torco is being used now.

    Can't really tell a difference but at least it's fressssh!

    Hey Meat, if you changed your stacks how difficult was it or did you send them off to Zdog? My dad has the ultimate set of tools, I fixed a toaster once, and I'd like to do my own revalve if possible.

    Dirty
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  9. Zerodog

    Zerodog Long timer

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    MR, Sanchez,

    You don't measure the fork oil height for WP open chamber forks with just cc's. It is a height measurement from the top of the fork tube.

    With the springs out and forks and cartridges colapsed measure from the top of the outer aluminum tube down to the oil. Depending on your application it varies in what you need. 120 is a great place to start for 48mm forks. 130 is good for 43mm forks. If you have 48mm forks 500ccs is really really low. It makes the fork like marshmelllows and might not even have enough in it to not cavitate like crazy. 100mms is about 600ccs. So about 570ccs is what you will need for 130 in 48mm forks. This is not perfect that is why you need to measure.
    #9
  10. meat popsicle

    meat popsicle Ignostic

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    Mr. Sanchez... :lol3

    Anyways, the specs posted by creeper above put the fork oil volume at 420 ccm (I think you mean cubic centimeters), so what gives? I ordered my fork oil based on that spec, and now I am short!?! :bluduh I need to order one more bottle...

    I just received my rebuilt, resprung, and revalved shock from Zdog - damn the thing is shiny! :evil I always appreciate that touch in service; another way of showing that you care about your work. Zdog - payment is on the way.

    I was doing my forks personally - without a revalve - but folks here (Luke and Creeper) convinced me that I should get them done while I am at it. So during my search for springs (0.52) I spoke with Superplush Suspension up in San Francisco. James agreed to revalve my forks (and check the internals) while I did (am doing) the rest.

    Very excited to try everything out! Oh, I am also installing Infinity Subtanks so I can soften the 0.52s for technical stuff.
    #10
  11. Luke

    Luke GPoET&P

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    Yeah, it takes slightly more than one bottle to refill a pair of forks.
    They have a very generous interpretation of circa.

    Can't you get the oil locally? There's so much markup on it that every bike shop carries several brands.
    #11
  12. Zerodog

    Zerodog Long timer

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    Yep it is just over 1 bottle. It is a bitch. You need 1 and a little bit. The 43 mm forks take quite a bit less oil. Knowing KTM and WP that is what the manual is based off of. You should be able to find Redline oil somewhere near you. That stuff is sold in almost every shop here in SLC. Glad you like the shock!! Wait until you ride it.
    #12
  13. bmwktmbill

    bmwktmbill Traveler

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    One way around the volume issue is to buy the oil from:

    http://www.mx-tech.com/

    He sells WP oil in bulk so you get extra.
    Has other parts, seals, shims etc.
    b.
    #13
  14. meat popsicle

    meat popsicle Ignostic

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    I'll check locally - I'd hate to pay shipping on one bottle.

    "capacity" IMhO means max volume, which appears to be over 600 ccm (ml) - what's that 50% more circa... KTM can circa my ass :fyyff
    #14
  15. meat popsicle

    meat popsicle Ignostic

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    No local dealers of their suspension fluids... so I ordered one more bottle from them online. $7 shipping is almost as much as the bottle :bluduh Thanks for the info folks - I'd better (try to) do a fork maintenance how-to with info like this.
    #15