KTM 690 SMC engine rebuild

Discussion in 'Thumpers' started by LethPhaos, Oct 11, 2014.

  1. LethPhaos

    LethPhaos Been here awhile

    Joined:
    Aug 16, 2012
    Oddometer:
    646
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    Belgistan
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    A while ago it turned out my primary gear shaft bearing on the clutch side was failing. This came at a bad time, so I ignored it for a while to ride the HAT first. The bike made it, winter is coming, so time for the rebuild.

    This is after only a couple 100 km (HAT + one day ride) on fresh oil...
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    I've never done anything like this before, so this is going to be interesting. There are not that many 690 rebuild threads around to learn from so I'm hoping to get some feedback from you guys to help me along :D

    So far I've removed the engine from the frame, nothing mayor, went easily enough.

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    Throttle body is rather dirty, I'll have to clean that up. I'm thinking I might have beein using too much oil on the filter. I don't trust the air box either, it seems to leak a bit on the bottom where the air temp sensor sits and between the rubber/plastic tube that connects to the throttle body.

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    My engine holding frame, it will help me keep the block steady while I work on it.

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    Everything disconnected, ready to remove the engine. I prodded the frame up with axle stands and supported the rear wheel to take pressure of the swingarm axle. I used a cross lift to lower the engine a bit, then took it out by hand.

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    Naked bike!

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    Ready for cleaning

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    Off course it started raining while I was out cleaning the block. Less work for me right :D

    That's it for today, ready to start on the real work next time.
    #1
  2. Pa_Lethphaos

    Pa_Lethphaos Would be adventurer

    Joined:
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    Good luck! :D
    #2
  3. larryboy

    larryboy Chopper Rider

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    Über Alles,California

    I'm thinking it's been sucking dirt instead of air, valves/seats/piston/bore are probably shot.
    #3
  4. JustBob

    JustBob Uh...who me?

    Joined:
    Dec 30, 2004
    Oddometer:
    908
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    Young Harris, GA
    Thanks for documenting this. I usually don't keep a bike long enough to need a rebuild but I may this one and it's always interesting to see how it's done.
    #4
  5. Schussboelie

    Schussboelie Been here awhile

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    I'm in!
    I won't be of much help but I'm looking forward to your progress. :evil
    #5
  6. gunnerbuck

    gunnerbuck Island Hopper

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    I'll follow
    #6
  7. thumpididump

    thumpididump MacGyver

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    Subscribed. :thumb
    #7
  8. mrwwwhite

    mrwwwhite Been here awhile

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    Oddometer:
    975
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    Bucharest, Rallying or RTW
    I'm in. Just finished rebuilding my 690 also (frame fracture) and plan to make a new thread with it.
    Good luck with the rebuild.
    #8
  9. hahmule

    hahmule Balding Gloriously

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    Jan 9, 2007
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    Nowhere Valley, CA
    lurking & learning:ear
    #9
  10. slidefighter

    slidefighter Gather it up, keep on...

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    South Carolina Low Country
    This is way cool and should be helpful to all serious 690 riders. I'm in..


    Lee...
    #10
  11. sprouty115

    sprouty115 Long timer

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    Providence, RI
    +1...
    #11
  12. MeinMotorrad

    MeinMotorrad Long timer

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    UK for now.
    In.
    #12
  13. LethPhaos

    LethPhaos Been here awhile

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    Aug 16, 2012
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    646
    Location:
    Belgistan
    welcome all, glad to have you along :)
    not a very productive session today, but any progress is better than none

    spent most of my time fabbing an engine holding screw, could have been done much faster but I shortened my only M8 bolt too much rendering it useless. ended up using a piece of threaded rod instead. painted it orange, so now it's better than the KTM approved tool :evil

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    with engine in TDC I started removing the external parts. done so far: oil filters, starter motor, gear sensor, alternator cover, valve cover

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    I don't like that rusty looking stuff, the picture makes it pop out more than it does to the naked eye though. humid workshop :(

    and here's my first question: how do you remove the countershaft spacer without damaging it? I didn't try any tools, but it seems on too tight to be removed by hand
    #13
  14. gunnerbuck

    gunnerbuck Island Hopper

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    The countershaft bushing is something that can usually be pulled out by hand, if not gently grip it with pliers and pull it out.. The sealing parts of the bushing are inside the case and not easily damaged...
    #14
  15. LethPhaos

    LethPhaos Been here awhile

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    thanks, I'll look at that next time.
    just ordered a flywheel puller, could take 20 days to arrive... this project is going to take a while
    #15
  16. gen

    gen Been here awhile

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    806
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    Asia
    in
    #16
  17. LethPhaos

    LethPhaos Been here awhile

    Joined:
    Aug 16, 2012
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    646
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    Belgistan
    finally received the flywheel puller, onwards!

    the countershaft bushing came off no problem, wasn't too tight indeed, used a rag to protect the bushing and took it out with some narrow pliers

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    I used an impact screwdriver on the flywheel nut (remove the engine blocking screw first!), it didn't feel like it wanted to move but I kept at it and after a while it came loose

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    removing the flywheel itself was a piece of cake, first I screwed on the puller, then I used a gas torch to heat up the puller and the flywheel briefly (less than a minute), started pulling and it popped right off. the garage was cold (15°C max) so the shaft was pretty cold as well in comparison

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    I also removed the timing chain tensioner, there should be an oring in there but I don't see or feel it, maybe I dropped it somewhere

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    larger pic of flywheel area, next up on this side will be removing the timing chain guides

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    but first I removed the water pump cover

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    5 nuts, the cover itself was on pretty tight, some convincing with a rubber mallet and some wiggling made it come off
    the top alignment pin and screw are rusty, which caused this, looks like the seal hasn't been doing it's job properly. the bottom screw is rusty as well, but not the pin for some reason

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    wheel and washer off

    then I moved on to the top end

    camshaft support plate, slightly marked but I don't think it's a problem. it's easy to replace in the future anyway, on one of the next valve services for example
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    camshaft itself in excellent shape, no pitting or anything. decompression pin in perfect shape
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    spark plug looking good
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    cam bearings look ok, I turned the big one by hand and it felt ok, I'm a bit concerned though, it feels ever so slightly gritty, as if there's 1 grain of sand in there somewhere, going to keep my eye on that as well in the next valve adjustments

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    time for my next pop quiz :D

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    1) the water pump cover seal didn't come off everywhere, what's the way to get this off? scrape with screwdriver? might be too risky for scratches?

    2) how do I get the big cilinder head bolts loose? I tried the impact screwdriver again for a little bit but I didn't keep at it as long as with the flywheel nut, should I keep going? they're really tight, the little ones were no problem to get loose
    #17
  18. yamalama

    yamalama wet coaster

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    vancouver bc
    Gunnerbuck posted up a great 640 rebuild.
    I believe it would probably be helpful.
    #18
  19. clintnz

    clintnz Trans-Global Chook Chaser

    Joined:
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    Rotoiti, North Is, New Zealand
    How many km on the bike?

    Screwdrivers don't work well as scrapers, too easy to scratch up the surface. Use a proper scraper or an old chisel & Be Very Careful! The aluminium is very soft compared to your tool! You can get plastic bladed scrapers which are supposed to be good but I've always got by with a metal one & a gentle touch.

    Warming the barrel around those head bolts may help bust them free but they should come out ok with hand tools. If you don't have a ~400mm strong bar for your sockets get one.

    I would recommend extending your engine stand so the engine bolts into it & it is held securely, that will make it much easier to put some pain on to remove any stubborn fasteners, and also make it easier when torqueing everything back up. When I rebuilt mine I chased the motor around the bench for a bit before taking the time to make a decent stand then wondered why the hell I didn't do it right at the start of the job.:D

    Cheers
    Clint
    #19
  20. Schussboelie

    Schussboelie Been here awhile

    Joined:
    Jul 22, 2013
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    836
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    Belgium
    I have several scrapers at home LethPhaos, both plastic (in two different thicknesses) and metal from waxing ski's. :evil

    What I first thought of is someting like this:
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    We use it for scraping glue, stickers and sticky dirt from flat surfaces like windows, our vitro-ceramic cooker and table top.

    Come pick them up any time.
    #20