KTM 640 Horrible engine noise!!!!

Discussion in 'Thumpers' started by moto_psycho, Feb 9, 2013.

?

What is the horrible noise?

  1. Cam chain tensioner

  2. Camshaft rockers / bearings

  3. Big end

  4. Gearbox main shaft bearing

  5. Crankshaft bearings

  6. Other?

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  1. moto_psycho

    moto_psycho Nob.

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    #61
  2. Dolly Sod

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

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    What kind of play? Axial? Radial?
    #62
  3. moto_psycho

    moto_psycho Nob.

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    Plenty of axial, not much radial. I'll make a video when I'm out of the bath
    #63
  4. moto_psycho

    moto_psycho Nob.

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  5. Dolly Sod

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

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    According to the shop manual, the tolerances for the conrod are:

    Radial: 0.05mm (0.0019")
    Axial: 1.00mm (0.04")

    My mark 1 eyeball says your axial play is within spec.


    EDIT Just went back and listened to your original video. What noise was it that was giving you worry? The loudest to me is a whirring from the left side. Mine makes a similar whirring when the motor is hot and the clutch is released. The noise goes away then the clutch is pulled.
    #65
  6. moto_psycho

    moto_psycho Nob.

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    More the "donk donk donk donk donk donk" noise, far more harsh when warmed up, and loudest at the front left of the engine, not really noticable when completely cold. Clutch nut was tight, and no change to the noise when clutch pulled in. 1st picture shows loads of swarf on sump plug, there was plenty on the oil change before that as well. Haven't actually seen anything with that much wear on it yet...

    sounded exactly the same as this video, http://www.youtube.com/watch?v=Cyq5_rYbeIo
    #66
  7. moto_psycho

    moto_psycho Nob.

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    Locked the crank and felt again, can't get any up/down play, even when just holding the piston. Now going to upload a video of play in the rockers etc... I honestly cannot find anything capable of making that racket!!! Piston slap perhaps?
    #67
  8. gunnerbuck

    gunnerbuck Island Hopper

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    Looking at the video it is easy to see that your con rod bearing is totally shot...

    Your piston and cylinder still look servicable going by the pictures... You can pull the piston rings and push them up in the cylinder to measure the ring end gap, I am sure they will still be within spec but you may want to replace them anyways... The rub marks on the piston do not look excessive so it should be good to go unless you find defects around the crown after carbon removal... The cases split quite easily on these engines as the tight crank races remain with the crank...

    Because you have had a con rod bearing failure I would also recommend you also replace the 2 crank end bearings as well because of the debris that has been washing around the crank chamber... You can take the bearing #s to a bearing supply shop and they should be able to fetch you a set at a more reasonable price... You will need a race puller to change them or better yet take your crank into a dealer and have them pull the races for a small {hopefully} service fee...
    #68
  9. moto_psycho

    moto_psycho Nob.

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  10. gunnerbuck

    gunnerbuck Island Hopper

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    That noise may be all due to conrod slap but I still think your left side crank end bearing may also be shot and part of the cause, you'll know better when you split the cases... What you could do now is remove the piston and spin the crank by hand and listen for a gravelly grating noise coming from that bearing...
    #70
  11. gunnerbuck

    gunnerbuck Island Hopper

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    #71
  12. moto_psycho

    moto_psycho Nob.

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    Do you know the part numbers for the crank bearings? Are they a pain in the arse to change at all?
    #72
  13. Dolly Sod

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

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    How do your exhaust seals look, any signs of blow by?

    I had an old XS Eleven that had a bad exhaust seal, which sounded just like a bad conrod. Once I got a new seal and torqued the header down properly it quieted right up. Exhaust leaks can sound just like mechanical knocking.
    #73
  14. gunnerbuck

    gunnerbuck Island Hopper

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    left side nj306c3
    Right side nj207ecp

    The bearings are not difficult to change it is the race removal from the cranks and re shimming to spec that are more of a problem...

    This page gives an outline: http://advrider.com/forums/showthread.php?t=632893&page=4
    #74
  15. Dolly Sod

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

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    From what I can tell the conrod bearing doesn't control the lateral play. There are two thrust washers in there that do that. But if the spec is 1mm, I'd measure it before I declared it shot.

    IMHO it's hard to tell just from looking at it.



    Gunner has a great thread showing how to change the crank bearings, and how to correctly shim them.
    #75
  16. gunnerbuck

    gunnerbuck Island Hopper

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    Unless I am seeing an optical illusion in the video it is very easy to see...

    When he moves the conrod the bearing cants over as you can see a gap opening up and pinching closed on one side of the bearing and not the other, this is not normal...
    #76
  17. Dolly Sod

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

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    Got it. It's not the lateral play you're worried about, it's that that conrod can rock on the bearing.
    #77
  18. bmwktmbill

    bmwktmbill Traveler

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    That's it, you can see the rod lift a little.
    The piston and bore look good and the rings too(so far).

    I'd replace the intake cam follower for safety.

    Moto psycho. Is there an oil mess in the bottom of your airbox?

    bill
    #78
  19. ericGSsti

    ericGSsti Been here awhile

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    What KTM thought was a fix wasn't. I noticed my engine was still noisey. I mensioned it to them when i pick it up. Said it was normal that those engine are just noisey. Clocked up 200 km on it and the noise got worse. Dropped it back to KTM this evening. Called the head guy out and started the bucket of spanners up. He was suprised and killed the engine staight away.

    Engines coming out for a rebuild on Wednesday. :cry
    #79
  20. moto_psycho

    moto_psycho Nob.

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    That sucks! I'd imagine they'd give you no reimbursements for false diagnosis either :p.

    Got the crank out of mine, bearings are A-OK!! :clap Just the rod bearing, now it is out of the case you can feel a minor (0.25mm ish) amount of vertical play. Hopefully just a case of replace that and the piston, and plonk it all back together :).

    Airbox was dry.
    #80