A new crankshaft I need?

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by Gluaisrothaí, Oct 20, 2007.

  1. Gluaisrothaí

    Gluaisrothaí Feckin' gobshite

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    I am starting a new thread, apologies if this is a faux pas....but I am anxious to say the least. My crankshaft looks in bad shape after a flywheel loosening episode.

    Any takers on whether this is repairable or I am in for a new crankshaft? BTW my 2004 turns out to be a 2003 spec bike- no woodruff key on the crank, and supposedly a TSB completed by lapping the crank/flywheel interface. Sheeesh.

    I guess this is also a lesson for anyone buying an '03 spec bike. Pull the generator side crank cover plug and re-torque the flywheel bolt. Please don't end up like me......

    Attached Files:

    #1
  2. cpmodem

    cpmodem Orange Caveman

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    The crank can be repaired by a well equipped machine shop, but since you will have to completely tear down the engine, you may as well install the upgraded crank (with woodruff key). I'm wondering if the TB was "botched".
    #2
  3. Gluaisrothaí

    Gluaisrothaí Feckin' gobshite

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    Any chance I could diamond paste grind, then use threadlocker on the taper as a temporary fix? I have the 243 type permanent stuff...I would worry about those gouges acting as stress risers and shearing the crank tip off at some point though.
    #3
  4. cpmodem

    cpmodem Orange Caveman

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    If you're talking about doing it with the engine assembled, just be very careful of getting any diamond paste into the engine. The threaded hole on the end of the crank goes into the oil passages. Sounds a bit iffy to me, butt hey, what have you got to lose at this point.
    #4
  5. Gluaisrothaí

    Gluaisrothaí Feckin' gobshite

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    Thanks CP. I feel the same way at this point....not too much to lose. The bike is out of warranty; whatever I have to get done to repair this properly is going to cost somewhere in the triple digits.....the crank alone is $700 without the tax. I'm sure there's a good 10 hours of labour there too at $80 per.
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  6. crazybrit

    crazybrit Long timer

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    You should be able to find a threaded insert (forget the name for them) you can temporarily put into the crank to prevent anything getting inside. Also, if the TSB was messed up, KTM may fix. I'd at least try and investigate that avenue.
    #6
  7. garyracetools

    garyracetools Adventurer

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    The crank end is repairable, without removal. Lightly clean up any high spots with a file. Put your lapping compound on the crank and the flywheel and lap away. This will take awhile. It will be obvious when you have a good mating surface. You can even add blueing to find high and low spots. Once you get that, clean the keyway and use a permanent locking compound. Torque the flywheel bolt and you should be set. I have done worse as a temp fix ,and they are still running around. I see this a lot with dirt bikes.

    Just make certain you seal everything off from metal particles and lapping compound. Like it was said "you have nothing to lose".


    Regards


    Gary
    #7
  8. cpmodem

    cpmodem Orange Caveman

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    CB brings up a good point. Do you know when your bike was manufactured? The date will give a good idea as to whether the rotor was lapped in at the factory, or later by a dealer mech. The former operation will not show up on the DealerNet, but the later one "will" show up, if the dealer entered it.
    #8
  9. Gluaisrothaí

    Gluaisrothaí Feckin' gobshite

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    >>Lightly clean up any high spots with a file. Put your lapping compound on the crank and the flywheel and lap away. This will take awhile. It will be obvious when you have a good mating surface. You can even add blueing to find high and low spots. Once you get that, clean the keyway and use a permanent locking compound.<<

    It will take a while. The gouges in the crank are about 0.005-0.01" deep. I'm afraid I'll run out of crankshaft before I get a good surface.

    Are you recommending I use something like Loctite 648 on the taper surface itself? Will this mean the flywheel can never be removed again?

    KL
    #9
  10. garyracetools

    garyracetools Adventurer

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    Use a Red locking compound on the threads. It can still be removed if heat is applied to the object. I use a heatgun to melt and remove Red Loctite. In your case if you are able to get this done correctly, you should never have to remove the parts. Just take you time and get the two tapers corretly matching each other. The better the job you do, the less you will have to rely on a thread locking compound.



    Regards.


    Gary
    #10
  11. garyracetools

    garyracetools Adventurer

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    Don't worry so much about the low spots. Make sure the high spots are all even. If you do have a lot of low areas, then you may want to use the locking compound on the crank also. I would try it without first. Again you have nothing to lose here. But like it was stated earlier you may want to see what a dealer says about the failure. If the work was done correct it should not have failed.



    Regards.

    Gary
    #11
  12. Flanny

    Flanny Flanny-it-up!

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    I dunno dudes...

    "You have nothing to lose" is very subjective...Like when you're a few thousand miles from home or a dealer you've got plenty to lose with a liability like that.

    With a spun flywheel on a MX bike, the worst failure of a "temp" fix is that you DFN a race. With a touring streetbike, the ante is up and the stake are much higher...

    If I found that on my bike, I'd pull the engine out of the chassis, tear down as much as I could with the tools I have, and then bring the rest to a known highly competent shop and work with the head LC8 wrech. You are in SF...Bring it to Scuderia...they are prolly' the best shop in the States...


    I guess if all you do is commute to work, then throw the dice...but if you use your bike for "Adventure Riding" then you should fix it right the first time....

    Just my $0.02

    (BTW - You can be sure I'd be back to the shop that did the TSB insiting like hell that they pay for the whole enchilada as a goining-in negociating position).

    Edit: Looking back at the picture, it looks really quite gauged...like really deep...If they were only some mild surface scuffing then I'd prolly just re-lap it...but those look like some bad-assed gauges...
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  13. hb7

    hb7 moto-science

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    Set it in a little JB weld.... and when you are ready to disassemble to properly fix it, you use heat to soften up the JB weld....
    #13
  14. garyracetools

    garyracetools Adventurer

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    JB weld and Devcon are used in industrial repairs of shafts with the same scoring as this. Use it to fill in the low spots like body putty. Then cement it in place. I had forgoten about this option. As long as you get the two tapers close, it can't fail. I used to be a Technical regional rep for one of the major motorcycle manufactures. We had this problem on a few of the big sportbike models. This was the temp fix for the customer until they could bring it in during the off season. Before you start anything though, find out who did the TSB. Either the taper was never lapped in or the bolt was never set to proper torque. I hate to say it but somebody messed up!

    Gary
    #14
  15. ridewestKTM

    ridewestKTM Long timer

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    See what I said on the other thread, but I would look into repair of parts before ordering the big items. A good machine shop might be able to do both parts. What's the risk in asking?
    #15
  16. Gluaisrothaí

    Gluaisrothaí Feckin' gobshite

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    I have tried lapping the crank and flywheel, but it's not looking too much better than before. I'm thinking about calling CC Rider and sending it to Scuderia West. I had it serviced there just before the mess (like 80 miles). Not implying any fault on their part. Any takers on what a crankshaft replacement might cost?

    It's a beautiful day in SF, all my mates are out riding, I'm thoroughly pissed off.
    #16
  17. cpmodem

    cpmodem Orange Caveman

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    ~$1100 for parts plus ~10 hours labor. You may as well install new pistons while your in there.
    Hey, an afterthought, butt how 'bout installing a 990 crank (for 980CC)? A little added stroke could make a wheelie machine [​IMG]
    Add the 990 pistons and you'll have the first carburetted 990 on your block.
    #17
  18. hb7

    hb7 moto-science

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    Slap the JB weld on the shaft, reassemble, torque to spec, locktite on the bolt.....at least try it. I wouldn't even bother filing/sanding/ shaping, just let the JB weld fill the voids. You have nothing to lose now but much more to gain...
    #18
  19. Gluaisrothaí

    Gluaisrothaí Feckin' gobshite

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    I'm thinking I'll basically have a new bike with run-in requirements. I agree with fitting new pistons or at least rings plus cylinder honing while it's apart. Anything else that should be taken care of?

    Would SW provide a x-mile/year warranty on the work?

    990 crank- nice idea!
    #19
  20. Gluaisrothaí

    Gluaisrothaí Feckin' gobshite

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    But possibly the PO did. Unlikely though as he owned it mostly during the warranty period.
    #20