How to service (some) LC4 forks

Discussion in 'Thumpers' started by meat popsicle, May 7, 2008.

  1. GodSilla

    GodSilla I did that.

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    Suspension is for Texicans. You could just turn the throttle and close your eyes, it works for some.


    Hi Meaty.:wave

    Mine's in the shed, unregistered, dead battery, glaring at my XR600. Around 50k now, prolly should do the cam follower bearings. My 640 suspension is well overdue for a service, the r.h fork rebound screw doesn't turn the full number of clicks anymore. I just turn the throttle and close my eyes........:evil
    #61
  2. TaxMan

    TaxMan Master of None

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    i'm doing some winter maintenance, checking and greasing my steering head bearings and re-springing my 2003 640 Adv. I was hoping to avoid replacing my fork seals, but i noticed that one fork had a very minor seep. i've never changed them, so i figured now was the time to go ahead and switch them out.

    i've been shopping for seals. can't bring myself to spring for the SKFs, but i'm also going to avoid the cheepos (MSR and Moose), mostly due to consistant negative feedback on them.

    i found a good deal on NOKs for seals for a 2002 640 Adv and wanted to see if there was any significant difference from the seals on the 03?

    I've checked the OEM fische on motosport. The 02 has a different part number, but the dimensions listed are: 48600057 OIL SEAL RING 48 X 57,7 X 9,5.

    The 03: 48600347 OIL SEAL RING 48X57,8X9,5 03

    I doesn't seem like +/- 0.1 should be a big deal, but I expect someone here can point me in the right direction?

    Thanks!
    #62
  3. bmwktmbill

    bmwktmbill Traveler

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    That's a new twist.

    Not sure what to say, checked my '02, NOK's for sure with a hard to read number, maybe BR6812 E..hard to make it out.

    Maybe call MX-Tech for clarification, or email them.

    http://www.mx-tech.com/
    bill
    #63
  4. gunnerbuck

    gunnerbuck Island Hopper

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    Even though both the 02 and 03 Adventures run 48mm forks for some reason KTM changed to a different fork in 03...

    0.1 MM larger shouldn't be too much of and issue... I would warm the outer fork tubes around the top with a heat gun just prior to tapping the seals in, this bit of heat expansion should make for an easier job to seat them in place...
    #64
  5. bmwktmbill

    bmwktmbill Traveler

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  6. Hipster

    Hipster Long timer

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    Taxman,

    If you want SKF seals, use KTM p/n R14020 for the SKF 48 mm fork seal kit (48mm forks) with includes the upper & lower bushings and the piston seal. The seal kit from discount KTM dealers is about $85.
    #66
  7. bmwktmbill

    bmwktmbill Traveler

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    If the Teflon is still good on the bushings you can go another 10K miles or more and save some money.

    Believe mine are still original at 50K miles.
    I've done seals a couple of times but that's me.
    bill
    #67
  8. meat popsicle

    meat popsicle Ignostic

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    Hola,

    in another thread there was a question about this assembly, and thought that the Husaberg forum had the answer, but while looking I came across mention of this upgrade:

    https://www.factoryconnection.com/M...roduct_Code=REBADJHOUSWP&Category_Code=FCSHKP

    Supposedly this seals the rebound needle assembly bore so it can't rust as easily, and at $25 a leg its not a bad deal either. Anyone tried this? Anyone have thoughts? I asked one tuner who know WP for his thoughts and will post if he replies.
    #68
  9. Droptarotter

    Droptarotter Long timer

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    Meat;
    That part looks to be for the rear shock, not the fork???

    I have some bicycle inner tube over that adjuster and the bottom pivot bearing on the rear shock............that seems to keep lots of the crud out.

    Cheers

    Cheers
    #69
  10. meat popsicle

    meat popsicle Ignostic

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    Woops - I think you're right... I found out about such a think from another forum, searched, and found that but didn't check to see what its for... maybe because I didn't know the rear shock was susceptible like the forks.

    Dang, I just heard back from a tuner who said he had ordered one and was waiting to try it, but I didn't specify forks... so he may have thought I was referring to the shock. I wrote to factory connection to check.
    #70
  11. wrk2surf

    wrk2surf on the gas or brakes

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    they are actually for the smaller bikes and not for the LC4 600-640 wp shock
    #71
  12. meat popsicle

    meat popsicle Ignostic

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    My bad - I probably read the thread at Husagerg.org too quickly and didn't catch the details.
    #72
  13. meat popsicle

    meat popsicle Ignostic

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    My mistake - I heard back from Factory Connection: they don't make any such widget for the forks. A very good WP tuner is testing this thing for a WP shock (may not be the same shock as on our 640s!) and thinks its a good idea. I wish they made one for our forks; but maybe its impossible. Too bad...
    #73
  14. ssbogger

    ssbogger Adventurer

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    I was using this thread, in conjunction with the forks owners manual as a guide to replace my seals. Everything came apart OK but when I was putting things back together and filling the tube up with oil I noticed something that I'm not sure is OK. When I pump the piston thru its full stroke, oil comes out near the top of the piston when it is almost fully compressed. It happens during the last inch of the stroke. See the picture below for where the oil is coming out. Note: I did not disassemble the pistons.
    Anyone have any ideas?

    [​IMG]
    #74
  15. gunnerbuck

    gunnerbuck Island Hopper

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    When you were refilling did some oil get into the cartridge assembly down through the tube? If so it will come back up and actually leak out of the rebound dial for a while when the forks are assembled..
    #75
  16. meat popsicle

    meat popsicle Ignostic

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    That was my thought too.
    #76
  17. ssbogger

    ssbogger Adventurer

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    No, I don't think so. If oil went down that tube wouldn't it come back out of that tube?
    The oil is actually leaking from exactly where the red arrow points to; between the aluminum nut and black plastic.
    #77
  18. meat popsicle

    meat popsicle Ignostic

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    Maybe something in the assembly is loose, allowing fluid to infiltrate and make its way up there. Thing is that's inside the forks, so I don't know if that is by design or indicating a problem. Best ask a fork tuner who knows WP good.
    #78
  19. gunnerbuck

    gunnerbuck Island Hopper

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    If oil is coming out there then it is just getting pressurized up from down below when you pump the damper rod down... What is happening is that the plastic guide bushing is hollow when you push it down into the oil the pressure escapes between that and the nut giving a bit of weepage... I would consider it normal and nothing to worry about...
    #79
  20. gunnerbuck

    gunnerbuck Island Hopper

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    What are the better oil seals out there now?

    The best I have used were the Athena fork seals, they have never failed, in fact the ones on my original bike have been in there for five years without leaking, the only reason I took them out was to replace all the fork bushings... The sad part is that they are no longer readily available...


    With no Athena seals available for my rebuild, I tried a set of moose seals {despite the warnings not to use them because they were junk}... In no time the left fork was leaking so I figured I must of messed up the seal and installed another new Moose seal... About 500 miles later that one started to leak too so I threw in an SKF seal into the left fork... Then after a 300 mile ride the Moose seal in the right fork gave out, so in goes and SKF seal to replace it... Now today the SKF seal in the left fork gave out I have 4 more of these seals kicking around but there is no way I'm going to use another one in these forks... So in goes my 5 yr old used Athena seal, I'll report back when it fails...

    Oh, by the way, I can find no defect, dings or jaggers with the fork tubes, sliders or seal seat and the forks never leaked a drop prior to the rebuild... The rebound needle was sticky so I cleaned it up and replaced the O-Ring but that was all I could find wrong during the rebuild... I also dropped the oil level 5 mm in each leg to add more air spring cushioning and reduce chamber pressure shock to no avail...

    I noticed that the garter springs around the top lip of the SKF seal are quite a bit smaller than those on one of the old NOK seals I had from prior... Maybe they just can't take the pressure...
    #80