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Starter won't turn the engine over

Discussion in 'XJ Technical Chat' started by Andius, Nov 27, 2020.

  1. Andius

    Andius Member

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    Hey all. Apologies if this has been covered, didn't find anything in a search.

    Reviving the XJ650 Seca after a long slumber. I've installed a new head, corrected by incorrect ignition wiring, and it was running! Rough, but running. But no longer..



    This is what I'm running into. I'd installed the new head following all the steps to align timing, there are no oil leaks, and I turned it over quite a few times with no ignition (unintended, but that should lubricate the cylinders). The bike was starting up pretty quickly until I suddenly ran into the issue in the video. I know I've run into this in the past, but it didn't persist as it is now.

    I have fears, but I thought I'd just put this out there to see if there's a simple issue and resolution here. Thanks!
     
  2. Franz

    Franz Well-Known Member

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    Can you turn the engine over by removing the cover on the left hand end of the crankshaft and rotating it anticlockwise?
     
  3. Andius

    Andius Member

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    Ah, good call. Just checked. No, not able to turn it over at the crankshaft anticlockwise.
     
  4. Franz

    Franz Well-Known Member

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    You should be able too. Remove the valve cover to check the valves. Sounded to me like the engine was locked, hope valves and pistons are not in contact. They should not have been if the engine ran freely. Don't try and turn the engine on the starter motor or with a spanner on the crankshaft again. Do you have any photographs on how you set up the engine timing?
     
  5. Andius

    Andius Member

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    No pictures of timing settings. I'll remove the valve covers and check the timing marks on the camshafts and report back. Assuming the timing marks will not be where I need them to confirm, is there any harm in rotating clockwise to line them up? At this point, I want to avoid pushing against any resistance.

    Thanks much!
     
  6. Franz

    Franz Well-Known Member

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    Have a look at the cams first you can turn the engine clockwise slowly, slightest resistance stop. Before you do that can you remove the spark plugs to see if the pistons are all roughly midway in the bores. Use a timber dowel or a large thin screwdriver or in the dark use a torch shone down the spark plug hole to see where the pistons are. I am hoping that the pistons are not touching any valves which would only occur if the cam timing was wrong or the engine dropped a valve. I have never heard of an XJ dropping a valve though.
     
  7. Andius

    Andius Member

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    Thanks. Interference was my concern as well, but having experienced this before and 'knowing' the timing is good, I wasn't too concerned. But that'll be the first think I look for, and will be careful doing so.
     
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  8. Andius

    Andius Member

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    https://photos.app.goo.gl/G77GDkgirQoQSXRr5

    Hope that link works. Camshaft markings look aligned. However the crankshaft marker appears quite.. off.. though I don't believe those spin 1:1? I should add I replaced the crankshaft sensor parts since (I imagine) a wrench displaced one of the magneto contacts.
     
  9. Franz

    Franz Well-Known Member

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    Crank moves 180 degrees and camshafts move 90 degrees. Did you line up the T mark on the crankshaft rotor with the line on the small plate held by the screw above the bottom pick up?
     
  10. Andius

    Andius Member

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    I did line up the T mark when reinstalling the camshafts. I have a Haynes manual, and while having done this before, I followed the steps.

    That said, this is all to my best memory and knowledge. I'm not above making mistakes, so if something is obvious, it may be true contrary to my statements..
     
  11. Franz

    Franz Well-Known Member

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    What is your battery voltage? As you had the engine running cam timing should be fine. Just trying to figure out why crankshaft won't turn.
     
    Last edited: Nov 28, 2020
  12. Andius

    Andius Member

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  13. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Load test it.
     
  14. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Fuel leak into the cylinders is the first possibility.

    OP, check the crankcase for gas.
     
  15. Franz

    Franz Well-Known Member

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    I was just thinking that hope you are right.
     
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  16. XJ550H

    XJ550H Well-Known Member Premium Member

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    yup a cylinder full of fuel will just not let starter spin motor. had this happen.
    started bike checked a few things when running. shut it down a few minutes later went to start locked up solid. pulled plugs out hit starter fuel sprayed all over the wall.
    if you do pump out the fuel when cranking disconnect spark plugs and tci do it out side or with a lot of rags over spark plug hole
    what a mess it can make let alone fire hazzard.
     
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  17. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    No rags. Those add to the fire hazard.
     
  18. Toomanybikes

    Toomanybikes Well-Known Member

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    This xj750k did in a big way
     

    Attached Files:

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  19. Yammaat

    Yammaat Active Member

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    Had that ones with a suzuki gs450. After a crash the petcock leaked and the bowlneedles were slightly off. 12L of fuel all down in the cylinders and below.
    Same story as xj550H was telling.
     
  20. Franz

    Franz Well-Known Member

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    Yes good picture showing the damage it did. I read in Motorcycle Mechanics magazine about a GPz 900 dropping a valve at Santa Pod years ago.
     
    Last edited: Nov 29, 2020

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