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XJ650 Seca Seized Engine Help

Discussion in 'XJ Technical Chat' started by Rebem, Jul 28, 2016.

  1. Rebem

    Rebem Member

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    Hi everyone. I recently purchased a 1980 (Australian model) XJ650 Seca from its second owner for the princely sum of $500, so although it looks complete, I'm under no illusions that it will be perfect. It has about 56,000km on it and although dirty from country dust, it's in excellent condition.

    I've progressed through a carb rebuild but when it came time to turn the engine over, electrical issues prevented me from doing so. However I can't even turn it over with a roll start or by crossing the solenoid terminals. It appears to be stuck hard. PO had described a flood of fuel from the carbs and then left it for a couple of years completely drained, so I'm guessing zero oil anywhere.

    So before I rip the head off and look further I was wondering if you had any obvious steps I could look at? So far I've done the following based on the extensive information on this site:
    - Removed and tested the starter - it's all good
    - Opened the left shifter case and looked through the inspection hole for guide breakage - all clear and in great condition in there
    - Poured ATF and Acetone in a 50/50 mix into the cylinders and left them for days, just bumping the bike in 5th to try to loosen up possible stuck pistons - no dice
    - Removed the left crank cover and used a 19mm spanner to turn the crank - little to no movement

    It feels like stuck pistons and I can deal with that but before I settle on root-cause is there anything else that can seize it?

    Thanks in advance.

    XJ650.JPG
     
  2. Toomanybikes

    Toomanybikes Well-Known Member

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    Next is pull valve cover and see if any valves stuck down with big clearance to cam
    Try diesel in cylinder and heat from head gun for a few hours or more
    Next is try a propane torch on each cyl
    Were any of the plugs rusty when you took them out?
    with no oil and was full of gas at some point rings are probably rusted to cylinder
    If all fails go looking for a spare engine (750is a direct drop in) just a touch of rejet or use 750 carbs
     
  3. Rebem

    Rebem Member

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    Thanks for the quick response! I'll pull the valve cover tonight then heat it up a bit after that.

    Plugs were surprisingly clean - bit rich on a couple of cylinders but no rust whatsoever.
     
  4. Toomanybikes

    Toomanybikes Well-Known Member

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    I'm out on the wet coast and I have had many bikes lock up after sitting a few years from rusty cylinders.
     
  5. MiGhost

    MiGhost Well-Known Member

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    You shouldn't need a complete engine. Just the cylinders and pistons if you find that the ones you have are badly damaged from the seizure.
    Not sure what the parts availability is in OZ but you could do a 750 crank, rods, pistons, and cylinders if necessary. Just be aware that using just 750 pistons on the 650 crank/rods will give extremely lower compression. You need the complete assembly if you go that route.

    The XJ750A would be your same bike with the 750 motor in it and was available in your market. Its also very possible that you might have gotten the XJ750E in your market which is a fuel injected version. Just to give you a couple possible option for parts.

    If you come across any OZ based parts diagrams in your searches. Please post the links for them. I would like to have a look at them.

    ~Ghost
     
  6. Rebem

    Rebem Member

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    Will do MiGhost and thanks for the feedback guys. I'm still hopeful that I won't need any parts given the good condition of everything else. The bike was in a shed in what we call the Wheatbelt which is inland country areas in Western Australia. Dry and hot during summer, dry and cold at night during winter.
     
  7. Rebem

    Rebem Member

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    Valve cover is off and all the valve clearances look fine. I'm wondering if I pop the head off or try heat first. Any opinions?
     
  8. Toomanybikes

    Toomanybikes Well-Known Member

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    Heat first with diesel in the cylinders. Try and
    Free up the engine before you pull the top end
     
  9. k-moe

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

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    If you can borrow a block heater that would be best. It'll heat the cylinders evenly without risk of damaging o-rings, or starting a fire. A heat gun will also work, or a torch with a diffuser tip.
     
  10. Toomanybikes

    Toomanybikes Well-Known Member

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    Have even seen a hot plat under the engine set about an nick from the oil pane and left for an hour or 2 and wrap cylinder wth foil to keep the heat in but remove exhaust first
     
  11. Nuch

    Nuch Well-Known Member

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    I have to say... that looks like a nice bike... especially for the price. Hope you free it with minimal expense.
     
  12. sybe

    sybe Active Member

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    how can you check clearances without turning the crank? If you turn the crank then the pistons are moving...
     
  13. k-moe

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

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    He couldn't have, without removing the head.
     
  14. sybe

    sybe Active Member

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    i quoted the wrong post! but... yes i think its odd he said the valve clearances are in spec

     
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  15. Rebem

    Rebem Member

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    Sorry, I wasn't very clear with what I said. The valve clearances looked fine, not in spec - i.e. there wasn't a huge clearance indicating a stuck valve.

    So by way of update, I used a heat gun for a while on the block (both sides) with penetrant in the cylinders. No difference so I got heavy with it and removed the head. Again, valves are fully retracted so no issue there. Cylinders have evidence of surface rust, particularly #2 and there was quite a bit of crud in there mixed in with the fluids. I've cleaned it all up and sprayed more WD40 in just to keep it soaking.

    Next step is to wait I guess. I'll keep trying to move it but is it possible it's something else? Just to cover my bases, I'm happy to eliminate other possible causes.
     
  16. k-moe

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

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    WD-40 isn't a penetrating oil.

    Make sure the transmission is in neutral. You might want to go ahead and remove the clutch basket just to make sure the transmission isn't the culprit.
     
  17. Rebem

    Rebem Member

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    Good point - I'll grab some diesel.

    I may have eliminated the transmission earlier when I tried turning the crank from the 19mm square plate thing under the left crank cover. It was in neutral and still wouldn't turn but now I have the head off I'll give that a go again.

    Thanks for the help so far guys. Very much appreciated.
     
  18. k-moe

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

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    If the shift forks are bent, the transmission may not be in neutral. If the alternator chain guide has failed, a chunk may be preventing the input shaft from spinning.
     
  19. Polock

    Polock Well-Known Member

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    take a block of wood and a hammer and tap the front then back of the pistons, not the top or sides. keep tapping harder, if it doesn't break loose, start unbolting your new boat anchor.
     
  20. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Seeing that there is no Airbox.... And not even pods on the carbs--- could be any number of things, not just rain, could have crawled in there....
     
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