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1982 XR500R with stuck piston/rings

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I just picked up an 82 XR500R that has the rings frozen up.  The previous owner said it sat in his garage for several years and when they got back around to it, it was frozen up.  The rest of the bike is really very clean for an 82.  I put different potions down the spark plug hole to see if I can loosen it up but no luck so far.  I first tried some Kroil, pumped that out then tried some Lime Away, pumped that out and now I have a 50/50 mixture of ATF and Acetone.  The rings/piston is still frozen.  I have been reading on there about some horror stories of taking these old (1982) bikes apart and not being able to find parts.  If I do take this apart, I assume I'm going to need a new head gasket, what else will I need and can I get the parts somewhere?  Any other suggestions out there?  I'm into this $100 but know I could quickly get into it more than it's worth in parts and labor so what are your recommendations?

Thanks all.

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I just picked up an 82 XR500R that has the rings frozen up.  The previous owner said it sat in his garage for several years and when they got back around to it, it was frozen up.  The rest of the bike is really very clean for an 82.  I put different potions down the spark plug hole to see if I can loosen it up but no luck so far.  I first tried some Kroil, pumped that out then tried some Lime Away, pumped that out and now I have a 50/50 mixture of ATF and Acetone.  The rings/piston is still frozen.  I have been reading on there about some horror stories of taking these old (1982) bikes apart and not being able to find parts.  If I do take this apart, I assume I'm going to need a new head gasket, what else will I need and can I get the parts somewhere?  Any other suggestions out there?  I'm into this $100 but know I could quickly get into it more than it's worth in parts and labor so what are your recommendations?

Thanks all.

 

I just picked up an 82 XR500R that has the rings frozen up.  The previous owner said it sat in his garage for several years and when they got back around to it, it was frozen up.  The rest of the bike is really very clean for an 82.  I put different potions down the spark plug hole to see if I can loosen it up but no luck so far.  I first tried some Kroil, pumped that out then tried some Lime Away, pumped that out and now I have a 50/50 mixture of ATF and Acetone.  The rings/piston is still frozen.  I have been reading on there about some horror stories of taking these old (1982) bikes apart and not being able to find parts.  If I do take this apart, I assume I'm going to need a new head gasket, what else will I need and can I get the parts somewhere?  Any other suggestions out there?  I'm into this $100 but know I could quickly get into it more than it's worth in parts and labor so what are your recommendations?

Thanks all.

i would suggest giving up and finding a newer bike as parts for a bike that old are scarce. maybe cut your loss by parting it out.

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I've quit taking in the pentroof 500s for repair completely. They have a tendency to become an ornament consuming floor space for years while you find parts. They need cam and rockers nearly as often as piston and rings. Parts are ridiculously hard to find.

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If I can't get the piston freed up, and I can find a motor, would it work to swap in a newer 600/650 motor?  Everything else on the bike seems good.

Thanks, 

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If I can't get the piston freed up, and I can find a motor, would it work to swap in a newer 600/650 motor?  Everything else on the bike seems good.

Thanks, 

No, any later motor will not bolt in. 

  Take the top end off it, see whats stuck. Whats the worst that can happen?

If the rings can be unstuck and things seem ok in there, , hone the bore and put it back together.

I'll probably get roasted for saying it, but if ya cant track down a new head gasket, and the old one is in one piece,, re-use it!

 I stuck my '79 back together the night before a Vintage MotoX (desparate times....) about 10 years ago with an old head gasket and its still hangin in there.

Edited by Muzz67

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You could be in for some heart ache with this bike but like Muzz said, just take off the head and see what you got. You may have a little trouble with the cam chain if the piston won't move -- I don't know this motor but my seized XL350 needed to have the cam chain cut so I could pull the head off. It probably will depend on the angle that the cam is in or it may not be a problem at all. You can only do what you can and if you get to a dead end, you just part out the bike on ebay and you'll recover your losses.

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The left side crank case was removed when I got the bike and the previous owner was thinking that a socket on the nut attached to the flywheel could be turned to get the piston lose after proper lube soaking has been done.  Is that right? I'm trying to let it soak for awhile before I get too crazy on forcing it to turn over.  Any recommendations on how to assist it in moving?

Thanks, 

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I know this sounds like total bs but honestly if you want to free it up go and pick yourself up some white vinegar, pour some down the spark plug hole. Let it soak over night. Try moving it back and forth with a wrench. If it moves slightly or doesn't move at all treat with more vinegar And let sit. Eventually you'll be able to move it back and forth quite a bit. When it gets to that point try pouring some oil in there and working it back and forth. Eventually it will turn over. Before trying to start it, make sure you drain the oil and put some fresh stuff in. I didn't believe it either, but my mechanic friend told me to do it. I thought he was pulling my leg. But it works better than anything I've tried!

Hope this helps

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Thanks for the reply and yes  I have already tried vinegar, I let it sit for about a day.  What do you mean by moving it back and forth with a wrench?  What should I move back and forth?

Thanks again.

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There should be an access hole on the gear shifter side that can be removed with a flat head screwdriver. Small one is for timing purposes and large one gives you access to the crank via deep socket and ratchet. Not sure of the size but it's used to time the engine, from there you can work the crank back and forth.

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I've cranked on that bolt described to the point that I was afraid it was going to break.  I've also rocked it back and forth if 5th gear and it still isn't moving.  I just put vinegar back in it and will let it sit for a few days and see if it moves as all.

Thanks for everyones input.

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Are you sure it is the rings and not something else in the tranny?  If the bike was stored indoors and was running when it was stored then I don't think the rings are going to be the problem. I can see that if it was stored outside under a tree for years.  

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Is there a way to see if the issue is in the tranny without taking it all apart?  I can put it in neutral and it rolls and it seems to shift through the gears ok, but maybe that doesn't really tell me anything.  Any recommendations to see if it could be something else?

Thanks,

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I bought an '88 "parts" bike like that. I was seized up pretty good. Long story short the timing chain busted and locked up the top end. Tear into her brother, she's yours. Good luck.

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