LC4 Sprocket seal replacement...

Discussion in 'Thumpers' started by creeper, Oct 29, 2005.

  1. clintnz

    clintnz Trans-Global Chook Chaser

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    Have a look at one of the parts websites like Munn Racing - they have online parts books. IIRC it's a common size available at any bearing & seal shop.

    Cheers
    Clint
    #81
  2. Ma77

    Ma77 n00b

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    32x47x7 seal and 25,00x2,00 o-ring (after you have read through 5 pages of idle chat)
    #82
  3. scottcolbath

    scottcolbath Long timer

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    Just finished my second seal swap on my 05 640. Done in 30 minutes, not including time inside to cool offf. It's friggin' hot and humid in Phoenix today.

    Props again to Creeper for his awesome documentation of this process.

    S.C.
    #83
  4. NKOrange

    NKOrange Puny homer

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    First, thanks for the instruction :clap

    I removed my sprocket and spacer, but not the seal. The o-ring is shot, so that will be replaced.

    I am assuming the leak was because of the damaged o-ring, and I am not planning on removing the seal. I'll replace the o-ring, put the spacer back (it is in good shape) and bolt the sprocket on. I thought I ask for some feedback from the experts before I do something stupid. Basically, do I have to remove the seal? :confused
    #84
  5. scottcolbath

    scottcolbath Long timer

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    Why are you so adverse to replacing the seal? You're in there. It's another ten minutes work.

    I guess the worst thing that could happen, is you replace the O-ring, and you still have a leak, and you have to go back in there.

    S.C.
    #85
  6. NKOrange

    NKOrange Puny homer

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    Well, it is stupid really but I did not order a new sealÂ… So, I'll replace the o-ring and see what happens.
    #86
  7. scottcolbath

    scottcolbath Long timer

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    Cool. Not a big deal if you have to go back in there anyway.

    S.C.
    #87
  8. regder

    regder Adventurer

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    Just bought an '06 625 SMC that is pissing oil out of the sprocket. It's so bad that I'll clean it up, ride it for ten minutes, oil is dripping down and the sprocket is soaked. I've already ordered all of the parts described in this post, as well as the sprocket nut washer as mine has something aftermarket on

    Is it possible for the countershaft seal to leak this bad or am I into something more serious?

    I've seen some mention that aftermarket front sprockets can cause a leak if they're too thin, does anyone know how thick it needs to be?
    #88
  9. bmwktmbill

    bmwktmbill Traveler

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    The KTM chain is not adjusted like a sport bike chain.

    Check your owner's manual for proper technique.

    Lifting the chain with your hand it should easily lay along the bottom of the swing arm.

    bill
    #89
  10. regder

    regder Adventurer

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    Chain is actually super loose, perhaps a bit too loose? Manual says it should just touch the bottom of the swingarm behind the front guide, I can probably get three inches to touch the swingarm
    #90
  11. bmwktmbill

    bmwktmbill Traveler

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    Perfect.
    It's gotta touch.

    bill
    #91
  12. NevBlu

    NevBlu Been here awhile

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    Counter Shaft spacer and O-ring

    Noticed that this thread was started 10 years ago, and continues to be relevant when LC4 owners experience a leak at the C/S. I am just finishing my complete engine rebuild (posted elsewhere), so here are normal parts:

    Permanent fix for 2001 KTM LC4 640 E
    Top row: Pressure washer and bolt
    Bottom row: KTM O-ring 25.0 x 2.0 [077 02 50 021] and spacer [530 33 01 7000]​

    After-market manufacturers have special pressure washers that are purported to have longer life than stock KTM water. Dirt Tricks is the company that comes to mind.

    Middle row: Short term temporary fix
    Only used for 6 minutes in garage and worked without leak.
    This one I would only use IF the spacer got lost while in a foreign country or if really desperate. It has not been subjected to any mileage, but hey, plumbing fiber washers and rubber spacer were available and <$3 at a hardware store.

    My manual says to use 33 ft. lb on the C/S nut. Use your manual for your proper value. This alone will reduce the chance of leaking, but more is NOT better for torque.

    I like some comments by others to use a wooden driver to tap the seal and/or spacer into place. I have some fiber glass dowels and even have used chop sticks. Good luck.
    :)

    Attached Files:

    #92
  13. regder

    regder Adventurer

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    So I'm doing the sprocket seal right now as we speak and have a question about the front sprocket lock washer. The one I took off and the new one that I ordered look the same, I thought it should be the large domed washer, but it's a small washer with a shoulder.

    Am I correct in assuming the shoulder should point away from the motor and hammer the shoulder down onto the flat edge of the nut to lock it?

    Looks like this

    [​IMG]
    #93
  14. NevBlu

    NevBlu Been here awhile

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    What Year, What Model, What size?

    For better help here, the above information in your post can help others help you. Do you have a manual, if not, this purchase is definitely worth the dollars spent? When items are removed it is a good idea to take note how these were initially installed even on scratch paper. When installing there are torque values too for the nut. From my experience, the domed washers are common. This part looks good and original, so can you speak with your local dealer or parts person? Good luck.
    :)
    #94
  15. clintnz

    clintnz Trans-Global Chook Chaser

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    There are 2 types of front sprocket retention on the 640 - the small bolt & dome washer, & the large 27mm aluminium nut plus the lock washer that's in your pic.

    Assuming you have the 27mm alu nut, yes, shoulder away from motor & hammer the edge of the washer up against the flat on the nut. I find I usually need a small cold chisel to get under it & get it started, then a punch to finish off. I always use a torque wrench on it - 60Nm - critical aluminium fasteners are not a place to go by feel IMHO :D

    Cheers
    Clint
    #95
  16. regder

    regder Adventurer

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    I mentioned it a few posts before, '06 625 SMC

    Quality info. It is indeed a 27mm nut. I installed same as you described, seems good so far.
    #96
  17. bikemoto

    bikemoto Tyre critic

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    60Nm + Loctite 243. :deal
    #97
  18. meat popsicle

    meat popsicle Ignostic

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    #98
  19. bikemoto

    bikemoto Tyre critic

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    Yebbut the 27 mm nut is re-used, so you have to re-apply the Loctite each time.
    #99
  20. meat popsicle

    meat popsicle Ignostic

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    I'm missing Mack today. :beer

    Yebbut I recall an engineer recommending that we replace the CS bolt-washer combo with each drivetrain replacement (I think that is KTM's recommendation too). Perhaps the fatigue concern was both the domed washer and the bolt.

    Since I'm not an engineer I went looking for good advice. Here's the best when it comes to reliability: (p.13 or 17 of 100 "Fatigue-Resistant Bolts")

    http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900009424.pdf

    It's a tad technical... how'bout something more straightforward:

    http://news.sherrylabs.com/laboratory-news-article.php?news_id=44

    Quote: "It was recommended that all bolts currently in service ... be removed and inspected at a minimum of 10X magnification for fatigue cracks in the threaded roots as well as any evidence of impact with the clamping device. If no fatigue cracks are found, the bolts could be reinstalled and torqued to their proper tightness."

    I never thought to inspect fasteners; maybe this isn't difficult? Here are lists of do's and dont's for fasteners that I learned more from:

    http://www.lce.com/Fatigue_Failure_in_Bolted_Joints_145-item.html

    http://www.bakerrisk.com/wp-content/uploads/2013/01/MEE_avoiding_bolt_failures.pdf

    Anyways if you cycle your CS sprocket more often (say you change out your gear ratios for different rides) then yes you must re-dope your CS sprocket bolt.