Fork Maintainence, complete or routine?

Discussion in 'Thumpers' started by dgrs2, Oct 28, 2003.

  1. dgrs2

    dgrs2 Where'd I leave my knee??

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    Is it OK to just routinely change fork oil, or should you always do a tear down and rebuild? I want to change fork oil on my 01 KTM 640 Adventure R and was wondering if I needed to totally redoo the forks? No leaks. Can you just clean the forks and add new oil? It's nothing to do that, but is it recomended? In the past I've always done the entire job, new seals, wear items so on. Can you get away with just oil change. Will it prevent premature wear? Is this something I should have always done?:scratch :scratch Who knows out there...........
    Oh ya by the way can someone possibly give jetting suggestions for adding a Big Gun full exhaust on the east coast? Or site where the info. is pretty good. Searched here but so many varibles. Thanx:jive :smile6 :bow
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  2. ShaftEd

    ShaftEd Long timer

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    I've always just changed the fork oil on a routine basis. Any bike I have with cartridge forks I change the fork oil every 6 months. Maybe a little less often for regular damping rod forks(i.e. the Dakar). I believe that the idea is, that regular oil changes will mean you do not have to rebuild the forks as often as wear will be less.
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  3. fixer

    fixer KLR-riding cheap bastard

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    i just changed the fork oil (and brake fluid) on my "new", 16 year-old KLR. (with only 6kmi)

    PO had NEVER done it :huh i'm planning on installing cartridge emulators in a short time, so i just drained, flushed with a small amount of fresh oil and filled... more complete service when i tear them down later.

    the old oil looked like somone let charcoal briquetes disolve in water... NASTY.
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  4. Stephen

    Stephen Long timer

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    Doesn't take 16 years to get :puke2

    I change it once a year whether it needs it or not...if I remember...which is why I started writing everything down in a little book...now where'd I put that book...dammit...
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  5. dgrs2

    dgrs2 Where'd I leave my knee??

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    What's the best thing to flush out the old crap with:slurp I remember in the past Marzocci forks used to get some nast spooge in the bottom of them. That crap was real hard to get out without a tear down. Anything less viscous then oil recomended:scratch
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  6. Stephen

    Stephen Long timer

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    No, I don't mean all the nice houses in my neighborhood, though some greedy bastards are trying.

    I mean you have to take your forks apart to clean the innards. I don't reckon flushing would be effective. Serious spooge to wipe outta there.

    Overhauling forks is not that big a deal, really, just make sure you have new seals and washers and such, and a tool to keep the damper rod from turning. Don't use solvents on the rubber/plastic bits. Don't scratch, bend, or crush anything. You know, the usual warnings, only more like brakes than motors. Oh, and do one leg at a time so you know how it's supposed to go back together.

    Let's see dgrs47 originally asked about the forks in a 01 640 R...those are old-school right-side-up forks, right, WP ? Shoot, drain and fill and go ride. No worries.
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  7. Frank Warner

    Frank Warner Traveller

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    As the fork oil is probably around 5 wt .. I would not use anthing lighter .. unless your stripping it down. Then meths, kero ... wot ever works for you...
    If your not stripping it down then just drain and refill with normal fork oil, drain and refill say 1 week to a month later. Do the second drain imediately after a ride.
    We should do a drian and refill at least every two years ... and that includes the brake fluid ... more frequently for higher performance / rugged conditions ... or more costly components that cost more when they ware out... its your bike and your money...

    Frank Warner
    Newspaper hides deteriorating journalism behind funky new layout
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  8. Mack

    Mack Gone, but never forgotten. RIP, Mack...

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    I think the 48mm WP USD's have 3 bushings, rather then the two the 43mm forks have, but this might only apply to the 525. (I just mention this, as I would think a "3 bush" fork would suffer less wear, and it seems the bushings and seals are the only things I find worn on the street forks I've rebuilt.) I've no practical experience to back up the following, but my plan with light offroad, non-competition use, of say 5-8k miles a year, was to flush the fluid the first year, and do an inspection and rebuild the second year. I would sure want the WP fork and shock manuals if I was doing the job, I snagged the CD off eBay. (Hmmm, that would be a good place to see about the bushings.)

    What about the shock? This is were I've heard more feedback about a noticeable improvement after a "rebuild." I just wish there was an easy way to confirm the shock is holding it's nitrogen charge.

    PS. I'm thinking about increasing the fork spring and shock spring rates on my 640 ADV R, and will be posting another thread to that end in the next day or so. The more feedback the better. Cheers, Mack
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  9. Bart

    Bart Constant Lurker

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    What I have doone in the past (for Damping rod type) is drain, put the plug in spray with WD-40. Move the fork leg up and down to allow the WD-40 to wash everything inside. Take the plug out, drain and then spray some more in the leg while movingg the fork up and down with the plug removed. I have not torn apart a Crtridge type so I am not sure whhhat materials are used to seal inside. A Damping type is all metal and Teflon. I have since started using Gas instead of WD-40 because it is cheaper and will leave less residue that will thin the new fork oil. Provided there is no rubber inside a cartridge fork Gas is the best cleaner.


    Bart
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  10. ram600

    ram600 Adventurer

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    PS. I'm thinking about increasing the fork spring and shock spring rates on my 640 ADV R,

    I put Race Tech springs in my forks and had to use KTM springs from an adventurer for the rear shock. I have a dualsport 640. I weigh 225 and found the difference unbelievable. I thought it was jsut all there was to expect from a 300 lb bike, but know it feels like a mx bike.

    Also for the fork oil I had the dealer replace it with ATF which we used to use before the marketing surge of 5, 7.5 and 10 weight stuff. Next time I am going to use synthetic ATF. I can't tell the difference in the oi between the original and the ATF. I think that ATF may lubricate better.
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  11. fixer

    fixer KLR-riding cheap bastard

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    yup, ATF is good stuff... perfect thing for flushing out the forks and what i used to fill mine this time.. i'm starting wioth light oil and installing new sproings as soon as they get here... then i'll play with viscosity and the cartridge conversion.

    yep, i know it doesn't take 16 years...when i installed the Progressive springs in my Katana with only abut 2K on the clock, one side was fine and the other was nasty... but that was more than 10 years ago, and now i realize that i filled the forks with too much oil, making them too stiff... oh well, that bikes long gone.
    #11
  12. dgrs2

    dgrs2 Where'd I leave my knee??

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    Nope up side down WP's Any worries???
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  13. dgrs2

    dgrs2 Where'd I leave my knee??

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    Nuts of replies:confused Can we narrow it down? I've done old school right side up. Now dealing with upside down. My new school, right side up on my past 01 400 SX was a total rebuild all the time. These forks on my 01 Adventure R seem to take more abuse over more mileage but wear less. what's the deal. And what is the beat cure for old fluids.:flush I could be missing the point....so please guide me down the right path.:bow
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  14. Mack

    Mack Gone, but never forgotten. RIP, Mack...

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    How about change the fluid, and see how it looks. If it's nasty then rebuild. Though it could very well look nasty and be fine, but as soon as you see ugly fluid coming out, it will be suspect in your mind, right? At that point I doubt I would be happy until I saw what the internals looked like. :(:

    I still say change the fluid every 6 to 12 monthes, and rebuild every other year. If it's just sitting, very low mileage I'd go longer, if it's ridden hard and/or lot's of miles, I'd rebuild annually. :huh :arg There now, it's all clear as muddy fork oil, isn't it?

    If your riding the ADV as hard as you should have been riding that 400 SX, your more of a man then me! :evil
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  15. dgrs2

    dgrs2 Where'd I leave my knee??

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    Thanks everyone:clap

    Not riding it as hard as the SX.......but the damn thing does go anywhere just alittle slower.:thumb
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  16. Bart

    Bart Constant Lurker

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    The Problem that I understood with ATF is that the Manufacturing is not as stringent to ensure viscocity is equal throughout. They are more worried about wear resistance and temperature variances.
    It seems to me that if you are concerned about the small changes in rebuilding every year, I would also be concerned about the quality of the oil you are putting in. Besides with a little knowledge in fork technolgy it is easy to shim and tune a fork yourself. Factory tolerances alone can give you a fork that is not up to par right from the factory (atleast on damper rod type). Using thin brass shims (even a strip of aluminum pop can) under the slider seals helps prevent leakage past the damper.

    Just my 2.5 cents.:huh

    Bart
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  17. fixer

    fixer KLR-riding cheap bastard

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    well... the AFT for both sides of the forks came from the same bottle... so it should be the same viscosity... will it be the same viscosity as a bottle of ATF off the shelf next time, dunoo, does it really matter? anyway, this is more of a short term fix to avoid tossing the the expensive fork oil when i install the cartridge emulators in a few months.

    yup, i'm a cheap bastard who rides a 16 year old KLR i "stole" for $675.00 and is currently running $1.00 worth of ATF in his forks... so sue me! :rolleyes:

    i think it was Flanny who said "ride it like you stole it", well at the price i paid for a bike with under 6kmi, i've been accused of doing just that!

    the whole damn bike is pennytek!
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  18. Bart

    Bart Constant Lurker

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    The point was that if you really think that a fork should be rebuilt with all new parts after one season of abuse and you will notice the differance, the oil you put in if it is a 10, 12 1/2 or a 15 is noticable.

    Bart
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  19. zimi

    zimi Adventurer

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    Hello, I am in the process of changing the fork oil of my KTM Adventure 640 2004. I was surprise not to be able to read anywhere, the amount of oil I have to put into each tube. They only say to measure it. I find it not very practival. I don't want to dismount the whole fork, just open the cover, empty the old oil (that looked like new to me) and add the correct amount of new oil whitout dismounting everything.
    Is it possible?

    thanks
    #19
  20. LukasM

    LukasM Long timer

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    No, on open cartridge forks you measure the air chamber length and not the oil volume. Too many variable to go with volume only.

    How are you planning to remove the oil if not by dismounting the forks? Even if you are going to remove the cartridge instead of turning the fork over - not any less work IMO - measuring the air chamber isn't any extra work.
    #20