Replacing valve stem seals: Anyone ever do it?

Discussion in 'Dakar champion (950/990)' started by wiseblood, Jan 30, 2015.

  1. wiseblood

    wiseblood OK, boomer Supporter

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    Continuing: So, getting the rings on, and the piston in the cylinder is a pain in the ass. Or, in the finger, as the case may be.

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    I am using a ring compressor with a key to tighten the loop around the piston. Even with that, it is really tough! (Tool pictured in upper right of this photo.)

    [​IMG]

    First one got in OK after a little manual work to get the top ring in. The second one... not so much. :bluduh

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    I managed to break the (brand new! $16!) oil scraper ring because the ring compressor was not closed enough, and I tapped the piston too hard. I almost think that just doing it all slowly by hand would have been better.

    Oh, well. New part ordered. At least ONE of them is done. :clap

    So, my next step was to put the cylinders back together with the heads.

    The heads were perfectly clean, but the cylinder side needed to be cleaned up. The head & base gaskets left quite a residue, and was nearly impossible to get off without considerable effort. Final solution was to use a "Roloc Bristle Disc" carefully:

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    (Thanks to @jdaniele for his help cleaning this up!)

    PRO TIP!: Now is an excellent time to do a valve adjustment! With the head removed, it's easy as hell to install the cams and simply rotate them away from the buckets. No timing == incredibly easy and fast to do. Which is good, because when you clean up the head, all your adjustments need to be re-done.

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    Now, it is time to install the head gasket. Make sure you still have the dowels installed to hoe the gasket in place!:

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    Before reassembly, I carefully swabbed all mating surfaces with brake cleaner to make sure there was no oil or other contaminant, anywhere. Place the head gasket on the head. It only fits on one way:

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    Interesting note!: The head gasket blocks some of the passageways! The coolant passages on the intake side are blocked except for two round openings, and the two smaller passages on the sides are blocked entirely. This seemed strange to me, but the old gasket was the same way. :dunno

    Fit everything together:

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    Don't forget the loctite #243!:

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    ...Then torque down. It's a two-step torque process. First, all bolts to 18 Nm. Then, go around again to 23 Nm.

    All done!:

    [​IMG]


    So, I'm waiting on a couple more parts which should come tomorrow. With any luck, I'll be able to update this thread again in a few days. :augie :hide
    #81
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  2. Dustodust

    Dustodust Long timer

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    END GAP on rings ?
    #82
  3. Dustodust

    Dustodust Long timer

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    With all shim and bucket heads, the valve adjustment is a vital part of the valve job. A good machine shop will know this and require that the head is brought in with the cams installed so that the range for top of the valve stem can be determined .
    After head/valve work no further valve adjustment should be required
    IMO
    hopefully you will be OK because the valves were not changed or lapped ?
    #83
  4. wiseblood

    wiseblood OK, boomer Supporter

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    Forgot to mention that!

    Old rings: Front was ok (0.4 mm), but rear was out of spec (0.45mm).

    New rings were between 0.30 and 0.35 (all rings). Service manual doesn't say what the MINIMUM gap is, though. :hmmmmm
    #84
  5. wiseblood

    wiseblood OK, boomer Supporter

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    Differences were very small, POST head job. All valves were in spec (I had adjusted them before sending off the heads), except for two: Front head left-exhaust (needed -0.05mm shim) and front head left-intake (also needed -0.05 mm shim) were very slightly out.
    #85
  6. Dustodust

    Dustodust Long timer

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    NEW piston pin clips ?
    I have heard of used pin clips coming out because they have lost their mojo or get out of round in the removal process

    I am not a machinist but from what I have heard is that the critical point IS minimum gap.
    Heat expansion can cause the ring gap to tighten and bind in the piston causing the piston to explode. ....
    Happens all the time
    a common misconception is that they are fine "out of the OEM box"

    (No such thing as paranoid when it comes to this type of motor ...LOL !!)
    #86
  7. wiseblood

    wiseblood OK, boomer Supporter

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    :nod

    That is actually the last part I'm waiting on! Should arrive tomorrow.

    :nod :nod

    I had a friend who knows these things calculate what the minimum gap should be, and what I got is OK. :thumb
    #87
  8. Dustodust

    Dustodust Long timer

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    Does KTM recommend NEW cylinder head studs ?
    typically "Bolts of Uniform Strength" such as these can only be used one time.
    When re-used they have lost their design elongation parameters and eventually a "mystery" head leak develops over time. Like you might get a few thousand miles out of it before it develops
    .....something to check on
    jus sayin'
    it is a common fatal mistake of home engine rebuilders on something like a V6 Toyota or Honda
    there could be an easily overlooked word in a sentence in the shop manual like " step 4, install the new head bolts"
    #88
  9. wiseblood

    wiseblood OK, boomer Supporter

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    It's a good thought. I just checked the service manual, and there is nothing in there which could possibly be construed as "renew bolts":

    Secure with Loctite 243 and tighten the three Allen bolts 3 to 18 Nm (1st stage) and 23 Nm (2nd stage).

    Dats it!

    The relevant sections:

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    [​IMG]
    #89
  10. DirtyADV

    DirtyADV Long timer

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    A rebuild usually requires a sacrifice in blood ...hell most tire changes requires that =)


    If I understand things correctly these three bolts just holds the head and cylinder together for installation and could theoretically be removed after cylinder assembly have been bolted onto the engine.

    Good to have them if doing like me and lifting cylinders and just changing base gaskets ...had the "Pyndon Syndrome" and when I saw damage to the engine cases I decided to not even bother looking at the valves. Just pulled the cylinder assembly up until clips could be removed and lifted them with piston in place and mounted back like that and I REUSED clips.

    But have kind of written off my 950 and bought a brand new 990R to replace it and just use the 950 with minimal maintenance until it gives up on me. Wont get anything for it if selling should I be honest about it so rather ride it until engine blows up and make a pile of spare parts out of it that day.




    Nice work so far. Its a bit anxious until its back together and running well.

    Good luck!

    /Johan
    #90
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  11. wiseblood

    wiseblood OK, boomer Supporter

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    I don't know about that! I assume that these bolts set the torque for the head gasket, and I doubt the bolts from the crank case were designed to hold both the base AND head gaskets in place. Probably, you'd end up with a head gasket leak in a hurry! (Keep in mind the cylinder-to-crankcase connection contains no coolant passages, so the demands are not as great as the head-to-cylinder mating.)

    Truth! :deal :nod

    I'm pretty nervous it will have problems when I put it back together.

    I'm being very observant of the service manual, and I'm being as meticulous as I can. However... I guess it's superstition: I've taken the bike apart down to its most fundamental parts. I didn't see "the magic" which makes it all work, and I don't know how it gets back in there. Hopefully, simple mechanical engineering and physics will be enough. :lol3
    #91
  12. DirtyADV

    DirtyADV Long timer

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    Quite sure there was a thread about it years ago that someone had lost one of the bolts with no ill effects from it.

    Since you do torque the nuts on top of the cylinder head harder then these 3 bolts the compression of the gaskets should increase once the cylinder assembly is bolted to the engine case.

    But I will not try removing them just for testing and if I would do a rebuild I would follow the manual.

    Hope"the magic" will be there even if it cant be seen =)

    /Johan
    #92
  13. wiseblood

    wiseblood OK, boomer Supporter

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    So, my NEW new oil scraper ring arrived today.

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    If at first you don't succeed.. blah blah blah. :fpalm

    So, just a tiny tangent on The Importance of Proper Ring Orientation.

    I've read at least one post from someone who rebuilt a 950, but put the oil scraper ring in upside down, and had TERRIBLE oil consumption. Here's why:

    [​IMG]

    This is a close up of the edge of the oil scraper ring. Close and against white it's easy to see it is asymmetric. Like any seal, the ridge faces towards the thing you're trying to contain. If you get it wrong, it's not gonna "squeegee" right, and you'll lose a lot of oil out the tail pipe.

    Fortunately, the ring is clearly marked on the top:

    [​IMG]

    :beer

    I'm still waiting for my damn piston circlips. FedEx was supposed to deliver it today, but at the last minute changed the date until tomorrow. :bluduh
    #93
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  14. wiseblood

    wiseblood OK, boomer Supporter

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    Busy, busy, busy!

    Since my last post, I've gotten my piston circlips, I've reassembled both cylinder / head assemblies. Last night I installed the rear cylinder/head. Some pictures!:

    First off, getting the piston w/ new rings in was a delicate task. Especially after I broke a ring the last time I tried! I went REEEEAL slow this time, and was very careful not to hit anything too hard or force anything. Piston #2, installed!:

    [​IMG]

    Next step was to install the head gasket for this (front) cylinder / head assembly. Same as last time:
    1. Swab both (clean) mating surfaces with brake cleaner on a fresh paper towel and let it dry, to remove any possible oil or other contamination.
    2. Install the locating dowels.
    3. Place the new head gasket on the (inverted) head
    4. Carefully place the cylinder / piston assembly on top of the head gasket, and make sure it is seated on the dowels.
    5. Clean the three bolts, and apply Loctite 243
    6. Install the three bolts. Two stage torque: First 18 Nm, then finally 23 Nm.
    7. Install the timing chain guide with Loctite 243, torqued to 15 Nm.

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    Some pro-tips!:
    • Assuming you're installing new piston wrist pin circlips, you should replace one of them before you put the piston back into the cylinder! It's an EPIC pain in the ass, and better to do it when it's easier to access it.
    • If you're installing one of the circlips, make it the side of the timing chain!! You will WANT to install the wrist pin OPPOSITE of the timing chain (for reasons explained more fully in the next message :deal).
    • After I installed and torqued the head gasket, I took a moment to use the Loctite 243 to tighten and secure the SAS block-off plates and the vacuum port bolts in the intake neck.
    #94
  15. wiseblood

    wiseblood OK, boomer Supporter

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    Next step is really the hard part: Reinstalling the whole head / cylinder assembly onto the crankcase.
    Having an extra set of hands (and, an ample supply of beer :beer) will help quite a bit.

    1. If you haven't already, remove the starter motor. It will make your job of getting the wrist pin / circlip in much easier!
    2. Set the rear to TDC. (We start with the rear first.)
    3. Clean both mating surfaces and swab with brake cleaner to remove any contaminants (oil, etc).
    4. Pull the piston down (but not OUT! :deal) of the cylinder. Do NOT pull it so far that the rings come out, or you will want to :baldy
    5. Now is a good time to put a little oil or assembly lube on the journal surfaces of the connecting rod and piston, where the wrist pin will be installed. (Personally, I found the assembly lube to be a little "thick" which didn't help as much as some engine oil.)
    6. Place the base gasket on the crank case side, make sure it's seated on the locating dowels. NOTE!: The front and rear base gaskets are NOT THE SAME! The front has the water pump and some different passages. It will be obvious if you try to fit the wrong one. :augie :D
    7. Slowly, carefully, guide the cylinder/head assembly down over the bolts. This is the time you're gonna want some help. You need to feed the timing chain up the tower, and you need to position the connecting rod so that it fits into the piston.
    8. Lower the assembly until the connecting rod exactly is in position in the piston.
    9. Slide the wrist pin in. This sounds a LOT easier than it actually is! :deal Extra hands help here, too. You have to slowly (without tools) work the wrist pin in, while wiggling the cylinder/head/piston to get the angle right. The clearances are SMALL, and even a very slight deviation of angle will make it impossible for the wrist pin to get in there. If you feel the urge to whack the wrist pin in with any tool, STOP, and have a :beer. Back off, and try again. :deal PRO TIP!: This is the point at which you will hopefully have installed the first circlip on the timing chain side. The reason is two-fold:
      1. If you didn't, then you will be fighting with the timing chain and at least one of the case bolts to access the wrist pin and circlip
      2. If you look at the cylinder, you will notice that there is a cut-away section. My guess is that this is here to make it easier to get the wrist pin installed without having to pull the piston too far down the cylinder. I didn't do this (:fpalm) and as a result I had to pull the piston just about flush with the bottom surface of the cylinder. VERY disconcerting!
    10. Now it's time to install the final circlip. If you haven't already, I recommend having that beer now. :beer :deal :deal :deal :lol3
    11. Place a cloth into the opening of the crank case. You WILL drop that f*&^ing circlip! Don't even imagine you won't. I dropped it maybe 10 times. At least. :fpalm
    12. PRO TIP!: Practice getting the circlips in with the OLD circlips before you install the piston into the cylinder. I did this half a dozen times until I had a system for installing it without bending it too much. Even if you practice, it will be 20 times harder when you're trying to work in the very confined space between the engine case and the cylinder.
    13. Try to avoid using too many harsh tools to put it in. DEFINITELY do not use pliers! I used a small flathead screwdriver to push/lever the clip in place.
    14. When you're done, check, CHECK, CHECK! Make sure the circlips are clearly and solidly in the groove. Look ALL around the circumference! A motor which loses a circlip and a wrist pin while running is.... ugly. :deal
    15. Once you have it all installed, it's time for another beer. You've earned it! :beer
    16. Now, clean the gasket / surface with brake cleaner on a cloth to remove the inevitable oil which had dripped on there.
    17. Slowly lower the cylinder/head on to the crankcase.

    Last part isn't nearly as hard as all that ^^^. You just need to:
    1. Install washers & nuts on to bolts.
    2. Torque as specified.
    3. Install timing gear over chain
    4. Install timing chain tensioner.
    5. Install shims & buckets.
    6. Install cams, and triple check timing!
    7. Install cam bridge and torque to spec.
    If you've gotten this far, all of the above is so easy you can probably do it in your sleep. Or, you can post instructions on the interwebz while operating on only 3.5 hrs of sleep. :snore :D


    Pictures!:

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    Wrist pin installed. No circlip yet!:

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    Circlip installed. Did I mention pain in the ass?:

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    Other side circlip, pre-installed before cylinder/head assembly:

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    Outer bolts. You can use a short 13mm crow's foot to get that one bolt which is too close to the "bulge" of the head case:

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    Inner bolts. These are easy. Just don't drop a washer down the tower! :eekers

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    Small outer bolts. These are low-torque (8 Nm):

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    Cam timing, rear, intake side. Note the "X" mark!:

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    Cam timing, rear, exhaust. Note the "X" (or is it a "+"? :lol3):

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    Rear cams face IN at TDC. (Front face OUT.):

    [​IMG]

    When I removed these cams months ago, I used a sharpie to mark the cam gears at TDC on the outside so I could more easily see when it was right:

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    I've marked the flywheel and engine case to indicate TDC. Hopefully this will make my job slightly easier:

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    That's it for now! :beer
    #95
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  16. StevenD

    StevenD Hmmmm, dirt!

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    Pro pro pro tip, ktm has a tool to install the circlips, takes all of 2 seconds with it :-). Good work, is mine next?
    #96
  17. Jdeks

    Jdeks Accepting and supportive of everyones feelings.

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    Mate, did you have your cylinders hone, plated, or otherwise treated before installing the new rings?
    #97
  18. wiseblood

    wiseblood OK, boomer Supporter

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    Do you have a picture of that tool? I saw a reference to it, but I couldn't figure out what it looked like!
    #98
  19. wiseblood

    wiseblood OK, boomer Supporter

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    I did not. Cylinders still had clean cross hatching, and didn't have any defects in the Nikasil plating.
    #99
  20. wiseblood

    wiseblood OK, boomer Supporter

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    Second cylinder done & installed!

    [​IMG]
    :rilla


    Install for this (front) was pretty much the same as the rear, with a couple small differences:
    1. Oil sensor install.
    2. On this one, the circlip to be installed was on the correct side, opposite the timing chain!
    Not to much to be said about #1. You need a 21 mm (22?) deep socket to get at it. And, it's much easier if the starter motor is out. 10 mn -- no big deal.

    Regarding #2: It definitely WAS easier to install from the side opposite the timing chain. You have more room to get fingers and tools in there. Pitchers:

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    Here is me holding the (not yet connected) connecting rod into position:

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    Piston wrist pin & circlip installed!:

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    Note the cut-away in the cylinder sleeve above ^^^. Note the lack of it on the other side, below:

    [​IMG]

    It's all good!:

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    Timing up the front was pretty easy. Marks are outside of the cam sprockets, and are dots:

    [​IMG]

    [​IMG]

    A keen eye will notice there are TWO sets of "dots." Notice which ones are used! If you got it right, front cams will point "out" like so:

    [​IMG]

    :beer

    My next steps:
    1. Going to rotate the motor a few times by hand to make sure everything is working correctly (timing is right, etc).
    2. Also, this ^^^^ will "seat" the shim buckets if they are not already, and then I'll do another valve check.
    3. Probably I'll do another leak down test, because I'm OCD like that. :lol3
    4. Start putting everything back together!
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