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Discussion Starter #1
Hi fellow AT owners, sorry for the long post.

My rear cylinders compression has gone down to less than 100 psi (front still ~130), and its leaking oil from head gasket and the bike is burning a considerable amount of oil. It has now gone more than 140.000 km. Still running ok, but doesnt have the same power as it used to have.

So from all I understand it's soon time for an engine rebuild.

I've talked with a few old AT owners and they seems to agree that most likely a change of piston rings, new valve seals and gaskets should do the job. Meaning theres a decent chance I dont need a new bore and pistons..

A friend in Australia, where my bike is currently running around, says he knows a guy who could probably help me with this. I know nothing about rebuilding..

So my questions is:
If the guy has rebuild ANY MC engine before, should I trust him to work on my belowed bike? I understand you need special tools to fit new rings, but besides that, is there any special knowledge required to do the work? I guess I can quite easily find the required tensions needed in haynes manual.

So in short - if the guy is not a trained mechanic, but says he can do the work, shoud I trust him on that?

I have new rings, valve seals and all gaskets for the work in my sparepart box.

Any input much appreciated. :)

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If he has worked on pistons before, then you should be fine. My only concern would be that if you are travelling, would it not be best to wait until you get home?
what if he disturbs something, even being a good mechanic this could happen. If that were the case, would this not be better nearer to home? Do you really want problems in the way back to Denmark?
 

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Discussion Starter #3
Thanks for reply John :) Yes I understand your point, but I'm really not sure where my bike is going next.. Probably not home to Denmark. I'm just worried that the issue might get worse and I would get stuck somewhere with a non working engine.. Not sure how long it can go on like it is now. I always heard compression below 100 psi is bad. And IT IS burning a lot of oil.. Not a good sign I guess. This also might be a almost "free" rebuild, which is great as I've spent almost all my savings travelling ;)
 

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I've just done something similar on my transalp, (i didn't change the rings but had access to them). It's an engine out job, only specialist tools i've used was a valve spring compressor to do the stem seals. (I needed an impact gun and clutch basket holder to change the oil pump chain as that was worn but not part of the work you mentioned).
The haynes manual covered the procedure pretty well, its quite a simple engine to work on so nothing too challenging and it sounds like you don't have a lot of choice but to take him up on his offer?

Actually I skipped some of the steps (checking for warpage/ovality etc) and you may need a cylinder honing tool and feeler gauges. Given the choice i'd rather do an engine swap than a rebuild
 

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Rebuilding these engines should be easy for a professional or an experienced at-home-mechanic. Don't count on only needing new rings. With that mileage, you may need to step up to the next size pistons. Frankly, if you are close, that is what I would do. Otherwise, you will just be going back into the engine after a year or two.

It would also be a great time to do a valve job. After 140,000km, your valve seats are likely robbing you of some power.

None of this stuff is hard to do for a shop or an experienced mechanic. An amateur? Probably not.
 

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Discussion Starter #6
Rebuilding these engines should be easy for a professional or an experienced at-home-mechanic. Don't count on only needing new rings. With that mileage, you may need to step up to the next size pistons. Frankly, if you are close, that is what I would do. Otherwise, you will just be going back into the engine after a year or two. It would also be a great time to do a valve job. After 140,000km, your valve seats are likely robbing you of some power.None of this stuff is hard to do for a shop or an experienced mechanic. An amateur? Probably not.
Thank you very much for reply. I will check the piston size also. I only have valve seals with me, but will look into what valve seats are.. Is it a big job to do them? Easy to get the needed parts?Hope the guy is competent enough. If not I will probably risk another 5000 km or more with the engine as it is. Still running decently with ony 100 psi on the bad cylinder, but burning a lot of oil.
Cheers, appreciate the input :)
 

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Burning oil could also come from valve seals. Lack of compression could come from valve or cylinder rings. If your cylinders are ovalized, changing rings won't change a thing. A rebore will be needed.

Look on Youtube how to determine if the lack of compression comes from the top or the bottom of your engine.
 

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Discussion Starter #8
Burning oil could also come from valve seals. Lack of compression could come from valve or cylinder rings. If your cylinders are ovalized, changing rings won't change a thing. A rebore will be needed.

Look on Youtube how to determine if the lack of compression comes from the top or the bottom of your engine.
Thanks Lee, will look on youtube when i have decent internet and see if I can learn a bit more about it :)
 
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