Misadventures in 990 camchain changing

Discussion in 'Dakar champion (950/990)' started by tomdubz, Jan 19, 2020.

  1. tomdubz

    tomdubz getting there Supporter

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    Decided to take on changing camchains on my 91k mile '09 990. Why would I engage in such torture? Whilst doing a prophylactic water pump rehab I noticed a little piece of broken off plastic jammed into the transmission gear down on the bottom of the sump. I assume this came off one of the timing chain guide rails. Maybe it was the cause of some clunky shifting that I've wondered about recently. Some precision chiseling with a precision screwdriver was necessary to dislodge it.

    IMG_20200120_100937.jpg

    For some guidance outside the manual, I've been following this:
    http://ktm950.info/how/Orange Garage/Engine/Cam/camchain/uk_mouse_chain_replacement/uk_mouse_camchain.html

    Stumped about how to pull off the highlighted

    Screenshot 2020-01-19 at 2.58.16 PM.png

    Mine seems pretty stuck. Manual has that handsy dude just reaching in and pulling like so:

    Screenshot 2020-01-19 at 2.58.02 PM.png

    Tried that to no avail. I assume I'm missing something.

    Rear is TDC.

    How should I "help" it?
    #1
  2. rinho

    rinho Rinho Féroce

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    Am I not understanding something ?
    First pic with the the hand taking the gear off has the comment "up to 2004"
    yours is "09, you need the special tool according to what's written on the same page ("05 and up)
    #2
  3. tomdubz

    tomdubz getting there Supporter

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    Doesn't that special tool just put it rear TDC so the dots are aligned? Is that when the wheels are retained by each other? Can't turn anything with the locking bolt in. Or were you referring to the bottom pic puller contraption? And have you done this before?
    #3
  4. uk_mouse

    uk_mouse Aquatic adventurer

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    If your engine has the split gear, the spring tension is probably holding it on the shaft. You can probably separate the two gears by getting a flat screwdriver between them and prising them apart. Careful as the spring might ping out when you do this.

    Assuming you've taken the cams out at this stage, I don't think it matters whether the engine is TDC or not. But there's no reason for it not to be. As long as everything is correctly aligned when you reassemble.
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  5. rinho

    rinho Rinho Féroce

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    I thought you couldn't remove the wheel, but the tensionning wheel is not apart yet... my message is then irrelevant.
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  6. tomdubz

    tomdubz getting there Supporter

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    Ooo the originator:
    Instead of the prising, I wound up using a beefy circlip plier. I'm afraid of sticking screwdrivers in a motor without that being articulated somewhere in a manual. One end on the spring indent and one on the sprocket's convenient hole. A good sqeeze made the spring shpoing. That'll be fun to get back together.

    IMG_20200120_094940.jpg

    Now, for my next trick, I'll figure out how to pull the balance shaft weight out. That seems pretty stuck as well. Manual eludes to using special tools (primary gear extractors) if you can't pull out by hand. I've got 59029021044, but that seems pretty useless in this application. Maybe I need to find something like 60029033000 that isn't +$100?

    Anyone got any better ideas?

    And I think it's time to change this thread title so you can all hold my hand while I bumble through the rest of this.
    #6
  7. tomdubz

    tomdubz getting there Supporter

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    Ok. So, prying with a seal puller worked to get the weight off. Prying the center from behind.

    Now I'm stumped on the woodruff key. Soaking in penetrating oil now. Any advise?

    IMG_20200125_130938.jpg
    #7
  8. Boatman

    Boatman Membership has it's privileges ;-) Supporter

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    A couple taps straight to the end of the key with a flat faced drift should pop it out.
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  9. tomdubz

    tomdubz getting there Supporter

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    That worked for the larger one for the weight. More like whacks than taps. I chickened out with the smaller one for the sprocket. I was afraid of marring the bearing and felt like the drift I had wasn't long enough to get in that angle comfortably. Maybe with the motor out of the frame this would all be easier.

    I was able to get the front cylinder chain out as articulated in post #8 here: https://advrider.com/f/threads/camchains-woodruff-key-stuck.619227/ and then I was able to get the new one back in too. Little bit of a rat fuck but it twerked.

    To remove, start turning counter clockwise while gently pulling with it like this:
    IMG_20200125_171635.jpg
    #9
  10. tomdubz

    tomdubz getting there Supporter

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    Well, this was vindicating. Tip of rear cylinder guide rail had broken off. That was the little plastic bit on the bottom of the sump. A simple check would be to peek next to the balancer shaft weights and see that your tips are still there. Old broken on the left replaced with the complete on the right.

    IMG_20200126_130907.jpg
    #10
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  11. uk_mouse

    uk_mouse Aquatic adventurer

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    Crap! I had the exact same thing happen, except in my case, the snapped off bit of plastic got caught in the cam chain, caused it to skip some teeth, and destroyed the engine.

    Good catch!
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  12. tomdubz

    tomdubz getting there Supporter

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    If you're ever trying to finger out how to preassemble the spreader drive start by consulting the manual (5-14).
    Screenshot 2020-01-30 at 7.41.05 AM.png

    Of course, it says you need special tools. You don't really. In the vise are a two appropriately sized and spaced sockets (one shimmed to make up difference). Rest the drive wheel's holes on the socket, have the wife hold it down, and spin the top bit with a pin spanner (not sure if that's what it's called). Use anything as a pin to hold them together. Something large enough to take up most of the hole worked better than something smaller. That same pin spanner majigger works for fork caps and holding the water pump wheel.

    IMG_20200128_220616.jpg IMG_20200128_220642.jpg IMG_20200128_220707.jpg

    It was a bit of a challenge getting the whole assembly back on the balancer shaft. I had to pinch and press them together while jiggling the pin just right in order to get them on without having to remove the primary pinion. I mean who has a 46mm socket lying around anyway.
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  13. tomdubz

    tomdubz getting there Supporter

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    In other snews, I made this shitty video. I think these are all normal clickety clacks, but I don't remember. Anyone want to tell me either way.

    #13
  14. uk_mouse

    uk_mouse Aquatic adventurer

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    I'm not sure I like the sound of that, but it's very hard to tell what the "clack" noise might be.

    Are you sure it wasn't your ratchet you were turning the engine with? :)
    #14
  15. ElwoodBlues

    ElwoodBlues Been here awhile

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    Difficult to hear on the video. Is the engine turning the correct normal way around? And maybe pull the plugs and turn it without compression, maybe it’s better heard that way.
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  16. tomdubz

    tomdubz getting there Supporter

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  17. tomdubz

    tomdubz getting there Supporter

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    Whelp, maybe I should've listened to the try turning it over without the plugs in.

    Won't start. Hearing a chuff sound from the throttle bodies. Will try to take a shitty video.

    Things that were done in addition to timing chains: plugs, valve adjust (1 intake on rear cylinder), water pump, starter o ring.

    Fuel pump works. Spark plug cap things are hooked up correctly. Battery charged.

    Where should I begin?
    #17
  18. tomdubz

    tomdubz getting there Supporter

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    Here's a video


    Got it to kind of start once I hooked the throttle up and turned it a little while hitting the button

    Stinks of gassy exhaust. Strangely, the front header is hotter than the cold rear after just a few seconds of running.
    #18
  19. tomdubz

    tomdubz getting there Supporter

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    I think this is where I fucked up
    Screenshot 2020-02-05 at 4.00.17 AM.png

    I misread the order of things here. First I put front cylinder TDC, removed cams, then put rear TDC, removed cams, and then proceeded with timing chain stuff from there.

    Was I supposed to do rear first, then front, then put it back to rear before proceeding? If so, how do I recuperate from my present predicament?
    #19
  20. uk_mouse

    uk_mouse Aquatic adventurer

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    It doesn't matter what order you took it apart, what matters is how you put it back together!

    I wonder if you've not given the crank an extra turn when going from rear TDC to front TDC on reassembly.

    Check the manual, but the order of reassembly is:

    set rear TDC and put the rear cams in
    turn engine 360 + 75 degrees anticlockwise to find front TDC
    put the front cams in
    #20