LC4 Steering head bearing, a how-to-guide...

Discussion in 'Thumpers' started by laramie LC4, Sep 15, 2006.

  1. todd83-900t

    todd83-900t Been here awhile

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    Ditto for me on the nasty rusty goo grease.

    On my bike there's a hole in the top nut, for the overflow tube.
    Stuffing the overflow tube down that hole just seems like a bad idea to me. Fuel and or water can flow down the shaft through the stearing lock slot and into the bearing. I'll be plugging mine.

    Bearings and seals:
    My bearing was a SKF 331274 W24 U which is an automotive wheel bearing. Good luck finding it, I couldn't find an online bearing supplier that stocked them.

    Todd '95 400RXC
    #41
  2. Odysseus

    Odysseus Stoic Philosopher

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    You are in luck my friend. One of our very own Thumperistas, Loaded, just happens to sell bearings for the KTM 640 ADV.

    Link:

    http://stenhouseracing.com/shop/index.php?main_page=product_info&cPath=2&products_id=7
    #42
  3. Dotbond

    Dotbond Africa, Africa

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    Well Mars,just got my steering head apart and cleaned all the grease/mud/goo like stuff away. Nothing rusty or worn but worse then i thought it would be after only 10,000km.
    Now i will go play with some new grease.
    #43
  4. Disquisitive Dave

    Disquisitive Dave Not so wise fool

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    I'll add another tick in the goo/rust column for the RXCs. I've got a '96 400.

    I think Todd is right about the fuel vent issue.

    [​IMG]

    I would guess they came up with the "fuel vent into the stem design" on their dirt/enduro models. Spilt fuel flows harmlessly through the stem, and exits onto the fender.

    When they dualsported the thing, someone thought a steering lock would be a good idea. So they milled a slot into the stem for the lock's bolt.

    [​IMG]

    So now every time the bike has a narcolepsy attack, "solvent" dumps directly into the bearing, especially when going over to the left. :doh

    [​IMG]

    The grease is then redistributed in a even layer on the lower tree. The existance of the slot allows water and other junk to get in there too, but it tends to not drain, making rust and pitting an issue.


    After cleaning (top bearing on the left):
    [​IMG]

    [​IMG]

    Any thoughts on sealing the slot? I didn't get the key for the steering lock, so it's not like it's doing me any good anyway.

    :bluduh
    #44
  5. laramie LC4

    laramie LC4 flying something...

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    i dont know if it will fit but you can see that my "newer" one does not have this hole (at least that i remember, plus looking at my pics). check and see if it would be possible to swap your old one for one from the newer models.

    it cost money but eliminates the issues. im always seeing people parting out their triples on ebay, you might keep an eye open and get a good deal.

    *edit* ooops- looks like they list the same part number for both the '96 and '03 models. so im not sure why yours is different ???? maybe i should go back and look at mine before i look like a fool and someone post a pic showing a big gaiping hole in mine....:loaded

    <TABLE cellSpacing=0 cellPadding=3 width=460 bgColor=yellow border=1><TBODY><TR><TD align=right>Part Number:</TD><TD align=left bgColor=white>50101033100</TD></TR><TR><TD align=right>Description:</TD><TD align=left bgColor=white>FORK TUBE L=244 '91</TD></TR><TR><TD align=right>Retail:</TD><TD align=left bgColor=white>$94.74</TD></TR></TBODY></TABLE>


    good luck,

    laramie :beer
    #45
  6. mars

    mars Starbucks anyone?

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    What about running a longer fuel overflow line all the way through the stearing stem? that would do a good job of sealing up the hole and prevent overflow from getting on the bearings.
    #46
  7. Disquisitive Dave

    Disquisitive Dave Not so wise fool

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    A longer vent tube would get the fuel by, but you're still left with the water/dirt issue. Ironic thought: without the fuel to disolve the grease, the water might be even less likely to drain... :lol3
    #47
  8. Odysseus

    Odysseus Stoic Philosopher

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    My bike, 2003 640 Adventure, must have a different steering tube design. It is one solid piece of aluminum. There is no chance for fuel from the vent hose to get to the bearings inside.

    That being said, I am in the process of de-crudifying the bike right now. http://www.advrider.com/forums/showthread.php?t=196098

    When I pulled the triple clamps apart, this is what my bottom bearings looked like:
    [​IMG]



    Several other LC4 owners have also commented that their bottom bearing was a rusty mess too. I'm scratching my head trying to figure out what is the problem here. Both the bottom and top rubber seals looked to be OK, but I replaced them anyway. The top bearing was fine. Does the steering stem bearings need to be cleaned and repacked every six months, instead of every year???? I doubt that these bearings were serviced before on my bike, I bought it used. But I really do not want to replace them again, it was a major PITA!!
    #48
  9. Dotbond

    Dotbond Africa, Africa

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    That is a seriously corroded stem and rusty bearing. Would make you think it's been in salt water.
    #49
  10. Dolly Sod

    Dolly Sod I want to do right, but not right now

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    Here's my super secret method to getting grease into that bearing..

    [​IMG]

    This little guy fits on the end of your grease gun,(gotten at advance auto) and is a needle that you can fit into that groove that you so want to fill with grease. Just go around the bearing and squirt grease in between each roller until it oozes out..
    #50
  11. laramie LC4

    laramie LC4 flying something...

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    i think the PO defiently got some salt water in the steering head. i saw your other post and my jaw about hit the floor when i saw that pic. i cant think of any other reason for something like that to happen. you said that the PO had left the bike outside by the ocean. im going guess there was enough moisture in the air and it got inside and that was the result.

    i always knew there was a reason i never took my dirt bike to pismo beach and instead rode my buddies cr250r 3-wheeler instead. i just knew that salt water and sand was the death of any fine machinery.

    laramie :beer
    #51
  12. Disquisitive Dave

    Disquisitive Dave Not so wise fool

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    Here's how I choose to plug the slot in the stem: JB Weld.

    [​IMG]

    I just hope that it doesn't fall apart over time. Just what I need: a source of hard crud right above my shiny new bearing.
    #52
  13. enduro-ince

    enduro-ince dirtslave

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    I'm pretty sure my bearings are toast, got some clickety clackety going on.
    So are these a standard type bearing or must I pay three times what they are worth and buy from KTM?
    Any one have a CHEAP source for these?
    TIA!
    #53
  14. Hipster

    Hipster Long timer

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    #54
  15. mars

    mars Starbucks anyone?

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    I paid 8 bucks apiece for them at our local bearing supply place.
    #55
  16. pitbull doug

    pitbull doug Been here awhile

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    Laramie simply a brilliant how to write up with photos at every step! we need more mechanics like you around here.The part I like best is the coldees that come with the project,great job Laramie. Oh Odysseus whats up with your rebuilding project, was enjoying that thread?Looks like the previous owner did some serious beach/salt cruising? :freaky
    #56
  17. R.Markus

    R.Markus Damage Addict

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    I just got done with mine and it does not have the slot.

    It's an '06 Adventure if that helps.
    #57
  18. Odysseus

    Odysseus Stoic Philosopher

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    Well I've spent the past 4 weeks waiting to get my suspension and wheels back. I've been doing little things like cleaning up the plastic bits, and obsessing over finding replacement stainless steel fasteners. :lol3

    I would have to say from what I can see the PO sure did enjoy the bike while he owned it. :lol3
    #58
  19. Ricardo Kuhn

    Ricardo Kuhn a.k.a. Mr Rico Suave

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    So can anybody tell me the exact size of those KTM bearings so i can make a few headtubes for my project

    yes I look around, but i did not see any information about the real ID/OD height dimensions
    #59
  20. ridelikeistoleit

    ridelikeistoleit slappy the hamfisted one

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    ok,from what i gather,if the bottom bearing is rusted recycle bin bullshit[as mine certainly is]the only option is to press stem out and replace[damn that arbor press down at harbor freight is looking better every day!]with new?alrighty then,I have checked the bleeping thread,and found some bearing part# but haven't seen any #'s for the rubber seals[1996 rxc620,shot,my own fault,95 rxc 400,preventative maintenance]maybe my eyes couldn't find it on ktmhutts 'fiche-'k any help appreciated! :1drink
    #60