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Crankshaft wobble - freshly rebuilt engine

Discussion in 'The Garage' started by CanadianSteve, Dec 10, 2019.

  1. Hey all, I recently rebuilt the top end of my (new to me) 78 XS650 SE. The following was done:

    New camchain
    New front and back tensioner
    New Wiseco Pistons and rings (second oversize)
    Machined out the jugs to fit
    New Boyer Bransden Ignition setup
    Cylinder head ported (intake/exhaust)
    Cleaned carbs, timing set, chain tensioned, etc
    Case was split and all gears cleaned and checked for wear

    The bike was running well for a very short period of time, in fact it was running awesome. Super responsive, smooth, started easily, I was happy. Got about 4-5 hours riding time on it and started to hear a high pitched squeal that increased with RPM. Looks like I have crankshaft issues as per the attached video.

    I'm pulling the engine again and will likely have the crank rebuilt, but I'm wondering what your thoughts/opinions are. Most of my questions will likely be answered when I tear it down, but:

    1) Do you think that the crankshaft was failing and the extra compression/power caused the failure?

    2) Do you think it was possibly a problem I created during reassembly?

    3) Do I scrap the engine and look for a used one with decent compression and cut my losses, or keep going to try and fix the current one?

    I welcome all thoughts and feedback on this one, sooooo frustrated!

    MaxPete and gggGary like this.
  2. Downeaster

    Downeaster Everything in XS Top Contributor

    I'm pretty sure the stock crank is just pressed together, so yeah, the extra compression and power may well have tweaked the crank, especially if it was a little tired to begin with.

    Hopefully, somebody that actually KNOWS will be along directly with a definitive answer.
    MaxPete, CanadianSteve and gggGary like this.
  3. Paul Sutton

    Paul Sutton Buckhorns on XV1000SE Top Contributor

    You may be able to keep your project going. After stripping down you could get the crank trued up again and have it spot welded to prevent future distortion. You may only need to replace that large ball bearing.

    I hope it is fixable.
    Last edited: Dec 10, 2019
  4. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    Yeah these cranks can do that, not frequently but sometimes, sorry it happened to you. I had one go in a couple minutes, after years of riding. I did an engine swap and never have pulled down that engine. But I did get some cranks welded up for when I get a round tuit engine build(s). Since it's the off season wouldn't hurt to snoop around see if you can find a good engine. Even if you elect to rebuild, might be better to start with a crank/bearings that haven't scissored.
  5. Hey guys thanks for the kind words, it helps me get motivated for the rebuild. I’ve got feelers out for a used 78 engine but might just get the crank rebuilt on this one. Won’t know for sure until I tear it down but this way my new pistons and porting efforts won’t be wasted.

    Paul, if I get this crank rebuilt and buy new bearings, do I do all three bearings (I think OEM# 93390-00003-00) or just one?

    thx guys, you’ve definitely lifted my spirits today.
    MaxPete and gggGary like this.
  6. Paul Sutton

    Paul Sutton Buckhorns on XV1000SE Top Contributor

    Sorry to admit but I am an amateur. Regarding the bearing replacement it will depend on whether or not the crank has twisted in more than one place. Whoever you get to true-up/weld the crank will be best to advise following their initial examination. If I were to get the job done I would replace all 4 bearings. Out of interest, did you observe any wobble on the alternator end?
    Last edited: Dec 14, 2019
    gggGary and MaxPete like this.
  7. OHRider

    OHRider XS650 Addict XS650.com Supporter

    Talk to Hughs Hand Built about rebuilding your crank.
    Team Junk, Jim, CanadianSteve and 2 others like this.
  8. I definitely would but I’m in Canada which complicates things a bit with shipping/duties etc. Will definitely keep the option open depending how the tear down goes.

    ..... engine coming out of the bike Wednesday night, then it’s tear down time.

    Jim and gggGary like this.
  9. lakeview

    lakeview XS650 Guru XS650.com Supporter Top Contributor

    Hi Steve. Where abouts in Ontario are you?There are more XS650 fans around than you might guess.
    Mailman, Jim and gggGary like this.
  10. Burlington :)
    88_pony, MaxPete, Jim and 1 other person like this.
  11. MaxPete

    MaxPete Lucille, Betty & Demi - I suggest but THEY decide. XS650.com Supporter Top Contributor

    I don't know where you are in Canada (its a big place) but from my experience, the one shop I would take that to is WolfeWorx in London, ON.

    EDIT: ahhhh - our messages must have crossed in the ether. You are in Burlington, so you are about 90-120 minutes from London on the slab.

    Terry Wolfe has worked on numerous XS650s (including mine and those of forum members the late RobinC, TotalFool and Lakeview) and he knows them inside-out. He is a licensed motorcycle mechanic and a journeyman machinist and is fully equipped to assess and fix the issue plus he has good access to parts suppliers.
    1040 Hargrieve Rd.
    Unit 1
    London, ON
    N6E 1P5
    Highly recommended.

    Last edited: Dec 11, 2019
    Team Junk, grizld1, Mailman and 6 others like this.
  12. Thanks Pete that’s definitely not too far, I will shoot him an email and see what he says, thank you so much for the info.
    MaxPete, Mailman and Jim like this.
  13. solo2racr

    solo2racr Suck, Squeeze, Bang, Blow

    I have rebuilt well over 100 single cylinder press together cranks but only one for a twin. If it were mine, I would re-true and then measure the rod play specs. If good, replace the crank bearing on that side and weld the pins in place. If it falls out of spec after the re-true, then rebuild. A re-true and spec check probably wouldn't take 30 minutes with the right tools.
  14. xjwmx

    xjwmx XS650 Guru Top Contributor

    If you can afford his prices you can afford the shipping! By private courier in a suit and tie. I had the same problem with my crank after about 60,000 mi. One day the starter caught funny and whomp. You heard it happening, Now I make sure I keep the button down until after the engine is running and the relay turns the button off. I read a story somewhere where back in the day a guy laid an xs650 crank on the counter at the parts department at a dealer and the guy there knew immediately what had happened. I'd ask on here in the classifieds for a new crank. One person was offering a great deal once, or on ebay, should be well less that $100 incl shipping (if you were in the states)
    CanadianSteve and Paul Sutton like this.
  15. Ok I didn’t know how much the HHB crank was going to cost, unfortunately that’s not something I can afford :(

    Well I was able to take the engine apart pretty easily since it had barely run. Some bearings on the crank look absolutely shredded. I’m told it might have been starved for oil so I guess next steps would be to investigate potential causes of this.

    Thanks again everyone for your help.


    Attached Files:

    Last edited: Dec 16, 2019
    Mailman likes this.
  16. Ok so a few things discovered. I can’t really make sense of it and would welcome your advice.
    On the middle crankshaft bearing that failed, three of the rollers are all scored but the rest seem fine. Also it looks like the other bearings are ok.

    The crank seems to have a bit of rust on the side closest to the failed bearing (picture attached). Also there are 2 chips in the case closest to the failed bearing.

    I would like to get the crankshaft rebuilt but I’m afraid if I can’t identify the cause of failure I’m going to just ruin another bearing when it’s back together.

    Any thing I should check or be looking for? Thanks again everyone for all of your help.


    Attached Files:

    MaxPete likes this.
  17. MaxPete

    MaxPete Lucille, Betty & Demi - I suggest but THEY decide. XS650.com Supporter Top Contributor

    I would simply take the entire mess to Terry Wolfe. You haven't got anything that he has never seen before and he will give you and frank, honest and correct assessment of the prospects for rebuilding that crank.

    If he says its a no-go - then just come back to the forum and I'll betcha dollars to doughnuts that someone on here can help you out - fast and cheap. The only potential downside is the cost of shipping a heavy assembly like an XS650 crank - but there are lots of folks within driving distance who may have spares and a roadtrip to meet a motorcycle buddy in the cold mid-winter is always fun.

    Just my $0.02.

  18. solo2racr

    solo2racr Suck, Squeeze, Bang, Blow

    Agreed. The later pics and descriptions make it seem like it's worst than I first thought. One bad inner main bearing will require a virtual total disassemble.
  19. MaxPete

    MaxPete Lucille, Betty & Demi - I suggest but THEY decide. XS650.com Supporter Top Contributor

    Yes - and that is a non-trivial task requiring some pretty serious machinery and if one bearing is toasted, I'll bet the others have damage too which renders the entire whole ball of wax -> scrap. Trying to cheap-out on a crank repair is a path that leads down into the depths of despair IMO.

    I could be all wet here, but my perception is that the XS650 crank seems to fail rarely. In fact, while I am fairly well calibrated on most other parts, I have no clue as the cost and availability of replacement bearings - but I'll bet they are not cheap or easily found.

    Paul Sutton likes this.

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