KTM 640 LC4 - Loud clicking noise when idle

Discussion in 'Thumpers' started by ciukes, May 18, 2013.

  1. ciukes

    ciukes ciukes

    Joined:
    Apr 25, 2011
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    25
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    Hi guys,

    Can you help me to identify source of loud clicking noise I can hear when idle?
    It goes away if I rev a bit and comes back when engine is back to idle.
    It comes from exhaust valves area. Can it be automatic decompression ?

    http://www.youtube.com/watch?v=yqmnOkkR4iE

    Any idea? Is this something to worry about?

    ----------------------------------------
    UPDATE:
    This is story has a happy ending.
    Jump straight to the final chapter if you are in hurry.
    http://advrider.com/forums/showpost.php?p=21566277&postcount=21

    ----------------------------------------
    #1
  2. Idle

    Idle Been here awhile

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    Is there any metal on the oil screen or the magnet?

    It sounds like the valve clearances are too large. If that's the case, the cam follower bearings (CFB's = rocker arm bearings) are suspect.

    If you find either intake or exhaust clearances way too big, the valve cover needs to come off to check the CFB's.

    When you pull the inspection caps, find TDC and wiggle the rockers up and down. Note how much if any movement there is, then kick the engine over 6-8 times or use the starter to turn it over.

    Then find TDC again and do the wiggle test again. If it's different, even a tiny bit tighter or looser than before, the bearings are likely toast.
    #2
  3. Seikkailu_R

    Seikkailu_R Been here awhile

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    Too slow idle and automatic decompressor working?
    #3
  4. Droptarotter

    Droptarotter Long timer

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    It sounds like it is idling high enough to stop the auto decompressor noise.

    Better check your valves and go from there!

    If valves too loose.......you might have a rocker bearing going.

    Idle nailed it!

    Cheers
    #4
  5. ciukes

    ciukes ciukes

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    Thanks you all for the advice!

    Yes, I found some small bits of metal on the magnet.

    I adjusted valves to the expected values.

    Damn... looks like this is the case.
    I know I should fix it ASAP but... how many more miles I can put on the bike before the engine will give up?

    Considering I can do the fix, is it the part #12 on the diagram we're talking about (rocker bearing) ?
    [​IMG]
    #5
  6. laramie LC4

    laramie LC4 crash test dummy!

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    depends, how much you like your bike? :wink:

    get it fixed, don't ride it until you do.

    laramie :beer
    #6
  7. bmwktmbill

    bmwktmbill Traveler

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    Don't try to ride it, you can do very expensive damage.
    You will have to rebuild the waterpump at the same time most likely if it hasn't been done so prepare yourself for that too....

    Think about what will happen if the bearing fails completely, think about metal in your oil and about your roller bearing crank.

    Just saying.

    You are paying, this is, the price of KTM 640 ownership.
    bill
    #7
  8. ciukes

    ciukes ciukes

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    The story continues...

    I removed the cylinder head top. Disassembled the rockers for inspection and found nothing alarming to my eye.
    Rollers are tight, surface is even. Visual inspection proves they're not oval.
    What do you guys think? Have I done all the checks to make sure rockers are in tip-top shape?

    All things together before disassembly
    [​IMG]

    Exhaust valves rocker
    [​IMG]

    Intake valves rocker
    [​IMG]
    #8
  9. bmwktmbill

    bmwktmbill Traveler

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    Ciukes,
    I don't know a way to be absolutely sure they are good except to completely disasemble the rollers. If they feel tight they are still good.

    I just replace mine every 15-20k miles and redo the water pump because I know they will fail.

    Gunnerbuck has a very good thread on rebuilding them in the index.

    I couldn't find his video but here's some of his wisdom.

    http://www.advrider.com/forums/showthread.php?t=659238

    We didn't see a picture of the metal on the magnet...were there broken pieces or just fuzz.

    If it's chunks, I'd keep looking.

    What year is your machine?

    bill
    #9
  10. ciukes

    ciukes ciukes

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    They're tight and roll smooth. Beside, if the problem were rollers then clicking sound would be permanent regardless the revs, right? In my case clicking goes away as soon as I rev up a bit.

    I done the waterpump, because the propeller was shattered. Not sure if that's related to the "clicking problem"
    [​IMG]

    I lost the photo:/ but what I found it was definitively fuzz forming a nice hedgehog on the magnet.

    It's 2001 with 6700 miles on the clock.
    #10
  11. ciukes

    ciukes ciukes

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    While cylinder head top is removed I went for crankshaft inspection. Focused on automatic decompression hoping to find something unusual that causes "The Damn Loud Clicking Noise"(tm) ;)

    I know auto decompression should be a bit loose to work but can't justify if what I see is correct. I'd like to save myself the trouble of removing camshaft and messing with timing, so before I go too far can you guys have a look and tell me what do you think? Auto decompression moves in all directions but always springs back to initial position ( see 0:06 to 0:10 ).

    http://www.youtube.com/watch?v=78KQ4uSbGv8
    #11
  12. bmwktmbill

    bmwktmbill Traveler

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    Ciukes,
    Fuzz on the mag is normal.

    Has the transmission bearing been changed?

    Got rocks in your skidplate?

    b
    #12
  13. ciukes

    ciukes ciukes

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    I don't think any sort of maintenance was done to the transmission. The gears change smoothly, I don't feel any problems. It has only 6,700 miles surely the gearbox can last longer than that. Am I wrong?


    Nope
    #13
  14. rz35027

    rz35027 Been here awhile

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    Where are the parts from the water pump? You don't want to leave them in the coolant tract....
    #14
  15. tundradirtbiker

    tundradirtbiker Been here awhile

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    Put a straight edge across the swivel foot adjuster for your valves. They tend to cup with age. If you measure a perfect .005 the center space is greater making more noise.

    Good advice on the bearings, my thumper chewed one and it was a mess. 400 hours max and I replace the complete rocker(s).
    #15
  16. Foot dragger

    Foot dragger singletracker

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    That's a lot of silicone goop stuck on sealing surfaces,that stuff can get loose and float around in the engine causing havoc and blocked oil passages.

    We need a thread devoted to Lc4 funny or not so funny clicking/clacking/clunking noises. Trying to diagnose engine noises on the internet is hard.
    #16
  17. ciukes

    ciukes ciukes

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    No worries... I checked all the pipes and tracked down every little bit.
    #17
  18. ciukes

    ciukes ciukes

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    It's the first time I play with liquid gasket. As you may guess I tried to do it right and went a bit too far. Now cleaning up the mess and redoing the silicone.
    #18
  19. ciukes

    ciukes ciukes

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    I did that and nothing wrong discovered.

    Correct me if I'm wrong but if there's something wrong with bearings/rockers/swivel foot/valves then noise would be permanent. It wouldn't go away as revs go up, right?
    #19
  20. ciukes

    ciukes ciukes

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    The story continues...

    Crankshaft is out for inspection. No alarming signs of wear, no loose bits. Auto decomp pin has proper shape, spring's length is above minimum limit.
    [​IMG]
    [​IMG]

    Inspired by The Miracle of Anti-Decompressants I decided to get rid of auto-decomp too.

    If click-clacking stops after assembly -> that was it. Otherwise I have a problem.

    Fingers crossed!:)
    #20