640 LC4 Sprocket Seal Question?

Discussion in 'Thumpers' started by b17flyguy, Mar 25, 2006.

  1. b17flyguy

    b17flyguy Adventurer

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    Hi, this is my first post. This forum is awesome and has been very useful. Just bought an 2002 LC4 couple of weeks ago and it is my first dual-sport/dirtbike.

    So here is my problem. I traced an oil leak to the sprocket seal (pretty bad one). So I read Creeper's guide to changing the seal and Meat Popsicle's guide to replace the chain. Great :D, now I know what to do!

    However, when I inspected my bike I found that the bolt is tight, but the spring washer is completely loose and the sprocket has a few mm of axial play on the shaft. Is this normal? (I don't think so from reading the guides)

    I also noticed that the chain is grinding :eek1 on the metal guide for the cover. So I counted and I have a 16T front sprocket and a 42T rear one with a DID 520 VM chain (covered in bits of metal). Isn't this the stock configuration? Why is it grinding? The guide is stamped 15/16T!

    I don't know if it matters but the bike came with Talon Hubs.

    I will take this apart as soon as I get some of that Loctite.

    Thanks for your help.
    #1
  2. mikeprod92211

    mikeprod92211 Desert Rat

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    How many miles on the clock?
    You may be due, hopefully , just for a sprocket replacement!
    Once you remove the counter shaft sprocket bolt, washer and sprocket, hopefully it's just the sprocket that is worn and not the shaft!
    If your chain is too stiff, dry, maybe rusty and not following the teeth properly and binding, that can cause it to bunch up and rub on the chain guide!
    You may need a good chain cleaning and lube, or if it's too stiff and rusry, a replacement my be in order.
    Keep us posted!
    BTW, I understand that OEM stuff works great, I myself have had great experience with Sidewinder chain and sprockets!
    #2
  3. b17flyguy

    b17flyguy Adventurer

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    The chain and sprockets appear to be fairly new and are in good shape. No rust, binding or abvious damage and tension is on the mark. The only thing wrong with the chain when I cleaned it is the little bits of metal that are being ground from the guide. The most important thing I need to know is:

    Is the sprocket supposed to have axial play in the shaft?

    Is the spring washer supposed to be loose and the sprocket able to slide back and forth on the shaft?

    Thanks for the help
    #3
  4. meat popsicle

    meat popsicle Ignostic

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    Hopefully the man hisself will show up and give you a hand with this. I would guess that there should be zero play in the shaft, and the play yours has is why the chain is grinding on the guide (a 17T will grind on it because it is too big for that model, but the 16T should be fine).

    I linked your thread into his so he can find you. :lurk
    #4
  5. creeper

    creeper Still alive...

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    Just to clarify... when you say "axial" I assume you are referring to the lateral movement of the shaft, back and forth in the case and not radial play, correct?
    The axial (lateral) play is normal... a max of .016" is allowed. It is the design of the shaft and the fitment in its bearings.
    Mine measures .013".

    [​IMG]

    As to the washer...
    The sprocket bolt has a shoulder or "step" on it that measures about .080", while the washer which fits over the shoulder, measures about .060" thick (all I have are used parts, so these numbers may vary).
    The washer is dished, so when torqued the washer compresses, tries to flatten out... but as there is no real clamp load on it other than the tension applied by the dished shape being compressed... it tends to rotate a bit. This by the way is what holds your sprocket laterally on the shaft.

    As to the chain grinding on the guide, assuming you've counted everything correctly, its sounds all stock stuff from the discription... all I can imagine is an incredibly loose chain.

    Best of luck,
    C
    #5
  6. creeper

    creeper Still alive...

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    Please note the corrected specification error in my last post.

    C
    #6
  7. gman350

    gman350 Been here awhile

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    If I am correct, what you are saying, is that you can grab your sprocket and slide it in and out on the shaft(without the shaft moving), even with the bolt tightened down?


    I can do that on my bike also.


    My 2001 LC4 came from the previous owner with stock gearing. I dropped a tooth on the front sprocket. I ordered the sprocket from a ktm dealer online, and doublechecked that it was the correct one after I received it. It is narrower than the sprocket that came on the bike.

    Not sure why it is like that. Mine isn't contacting anything though, even when I slide it all the way in or all the way out.
    #7
  8. b17flyguy

    b17flyguy Adventurer

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    I worked on it some this weekend. To clarify I am talking about the sprocket being able to slide in and out of the shaft, even when the bolt is tight. The sprocket has so much play that the clamp washer doesn’t even contact the sprocket.
    <o:p> </o:p>
    Meat is right about the guide :bow . I notice that the sprocket slides so far in that the chain links grind against the guide. When I slide the sprocket all the way in it is obvious the chain is out of alignment too. So I am pretty sure this is not normal.
    <o:p> </o:p>
    From the parts diagram it looks like the clamp washer outer edge is supposed to rest on the sprocket, the sprocket rests on the sleeve and the sleeve rest on the silicon O-ring. The O-ring rests against the bearing which is supported by the engine case. My guess is that the O-ring is either gone or so damaged that it allows for sprocket to slide in and out of the shaft. It could also have the wrong thickness sprocket or the wrong thickness sleeve. I can’t imagine an O-ring being able to seal with all that play in the assembly. With no pressure from the sleeve how can it seal, right? That might explain my major oil leak!
    <o:p> </o:p>
    I won’t be able to take the wheel and chain off until next weekend (No garage, no lift, no center stand and very little time :cry ) but I’ll post the results.
    <o:p> </o:p>
    Any comments are welcome!
    <o:p> </o:p>
    Thanks
    #8
  9. meat popsicle

    meat popsicle Ignostic

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    I was wrong about the play, so quit yer bowing! Luckly for me I was just guessing...

    Perhaps a pic would help (yours if you can post one). Here is mine:
    [​IMG]

    That is a 16T CS sprocket. Note there is very, very little room between it and the 'guide' I thought you were talking about - the one that holds the CS sprocket cover screws.

    So what are you talking about - "the chain is grinding on the metal guide for the cover"... ? If the shaft is sliding in/out of the case (i.e. the same movement you would use to pull the CS sprocket off the shaft or put it back on eh?) then it shouldn't make the chain hit the guide. In regards to the chain grinding, either:

    1) you have more play of the kind that creeper detailed above, which is more likely to allow the chain to hit the guide,

    2) or you have a 17T CS sprocket,

    3) or you have a bent guide... :dunno

    (NOTE: more guessing but there is a process of elimination to go thru)

    In regards to the leak, creeper did say in his guide that if you leave the CS sprocket off for a time the seal would start to leak, so I am thinking you are onto something that the play might be part of the leak. How thick is your CS sprocket?

    Here is my CS area cleaned up a bit (not as much as creepers of course :D):
    [​IMG]
    #9
  10. b17flyguy

    b17flyguy Adventurer

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    That is the guide I am talking about!

    The play is not the shaft sliding in and out but rather the sprocket sliding on the shaft

    Nope, it is 16T I counted it twice and then again. When I pull the sprocket out against the clamp washer there is no interference with the guide.

    I don't thinks so, the guide looks good. I think the sprocket slides so far in towards the engine resulting in the chain being out of alignment to the guide. this results in the chain links grind on the edge of the guide.

    The big question is why the sprocket slide so much on the shaft towards the engine :dunno

    Hopefuly I'll find out next weekend

    Thanks!!!!!!

    You guys are cool :jkam
    #10
  11. meat popsicle

    meat popsicle Ignostic

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    That sounds better than the shaft sliding in and out - look on the bright side! :lol3

    How far is that movement?

    I would ask what CS sprocket is it - KTM part, the correct KTM part, or?

    And from my one time of being there (:lol3) I can't say I can picture enough movement of the sprocket to allow the chain to be far enough out of alignment so that it rubs on the guide. I guess it really is that close...
    #11
  12. creeper

    creeper Still alive...

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    I think I know what's going on now that I've had time to chew on it. If you've already figured it out... sorry I'm late to the party.

    You say your washer is loose, you have sprocket lateral play, an oil leak and the chain is hitting the guard.

    This is what's happening.

    [​IMG]

    The loose washer (22) is allowing the sprocket to move laterally, which allows the spacer (25) to move laterally, eliminating the compression on the shaft sealing o-rings (19 & 21). This, unless your seal is shot as well, is the cause of your leak.
    It is also likely the cause of your chain hitting the guard. If the sprocket has been moving for some time, it may be loose on its splines, allowing radial eccentricity and cocking... which would I believe allow the sprocket to come into contact with the guard.

    Thats my theory... and I'm gona' hang my hat on it for awhile.

    Ciao,
    C
    #12
  13. ChrisC

    ChrisC Amal sex?

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    So to simplify what Creep said, your tellerfeder is too loose causing your kettenrad to move on the shaft... are we gettin' this?
    :D
    #13
  14. d0gWateR

    d0gWateR Goat Stuntaz DSMC

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    Creep's suspicion is correct I believe. I had same problem on my '03 640 Adv, you are supposed to replace that bolt and spring washer each time you replace your countershaft sprocket (or whenever the washer doesn't seem "springy" any more). It comes as a set, and cost something like $6 (and comes pre-loctited!) KTM Part# 590.33.034.044.

    I went through the same BS, changed the CS seal, changed the o-ring, still leaking WTF!!! My washer was flattened as well, and allowed just a tiny bit of movement. But that was enough to allow oil to leak past that little o-ring on the back of the spacer, and oil would run down the splines and fling all over the place. Messy!

    The new bolt and springwasher fixed the problem permanentlty.

    Good luck.
    #14
  15. b17flyguy

    b17flyguy Adventurer

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    I am pretty sure now that the silicone O-ring is so damaged that it is the cause of all the problems (at least that is what I am hoping so). I don't think the washer is the cause of the porblems :nah since I can push (slide, not cock) the sprocket in, it will go so far in that the chain links will hit the guide. If I pull the sprocket against the spring washer the the chain rollers are in alignment with the guide, the chain links stay clear on both sides and it just looks right.

    My guess is that the O-ring is squished flat resulting in improper spacing, or maybe flat out gone. I guess I could have the wrong spacer bushing or maybe a aftermarket sprocket that is to thin.

    Thanks for all the help. After I work on it I will Update:type!

    ALL I want is a HAPPY and aligned kettenrad.

    Hey dOgWateR that is a cool avatar!
    #15
  16. b17flyguy

    b17flyguy Adventurer

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    I got my oil leak fixed!!!:clap

    It turned out to be the front aftermarket sprocket was too thin!

    But hey a picture says a thousand words!

    DSCN4115 copy.jpg

    http://www.advrider.com/forums/attachment.php?attachmentid=71288&stc=1&d=1144971259

    The Black sprocket is the new KTM factory sprocket, the silver one is a PBI sprocket. The thin sprocket resulted in improper location of the chain, grinding and an oil leak.

    Thanks for all the Help
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  17. acupuncture4u

    acupuncture4u Freedom by knobbies

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    #17
  18. KTM640Dakar

    KTM640Dakar Motorsick

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    #18
  19. eaglej

    eaglej Been here awhile

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    I have done this exact same thing. With the short shoulder, the sprocket is really loose on there- no oring compression at all. My bike oil went to the bottom of the sightglass in 15 miles.

    If your spring washer is flat, you can reform the dome on it a few times- I have used sockets and a press (a vise could work) Skinny socket on the inside flat, large one around the perimeter, and a little tweak tweak with the vise will put the crown back. Of course it isn't the same as it was blah blah blah, but if you don't want to wait a week for a stupid part, it gets the job done.

    J
    #19
  20. GodSilla

    GodSilla I did that.

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    Whenever you pull the front sprocket off you should replace the washer and bolt. The parts are cheap, as someone else mentioned, and why skimp to save six bucks and risk thousands of dollars?
    IMHO the setup sucks, and later models have a different, more conventional arrangement, but hey, we live with what we've got.

    Hi Meaty.:wave
    #20