Adopting another problem child

Wingedwheel

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I have to clean up the pistons still but yea I can do that. What are you telling me? JP you have to remember I’m usually the guy learning on the fly. What issue are you referring to with boring the liners And what am I looking for with the piston skirt?
 

jpdevol

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If the new-to-you liners are clean and you can get within say .005" on used piston, it'll be ok. New rings could be within tolerance <.024" @ std bore and you can always get new 1st over rings and file the ends.

IDK how one would fixture bare liners properly to get a square and true bore, except by using a Sunnen type hone set-up. Bore needs to be square to base gasket surface, etc. (more...)
 

Wingedwheel

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If the new-to-you liners are clean and you can get within say .005" on used piston, it'll be ok. New rings could be within tolerance <.024" @ std bore and you can always get new 1st over rings and file the ends.

IDK how one would fixture bare liners properly to get a square and true bore, except by using a Sunnen type hone set-up. Bore needs to be square to base gasket surface, etc. (more...)
Again, not a problem I’ve dealt with in the past so I’m open to suggestions. I have heard of the filing OS and the shop needs the fins to bore squarely? That is something I didn't know and I would have thought they could be squared off the lip. Liners are nice and clean. I don’t understand how you can get the stock rings that close because that was an issue with my 76 when I was having the low compression issue and oil blow-by. End gap was .028 on the one side but it was the rings.
 

jpdevol

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If the bore dia. itself is good and the piston skirt (90* from wrist pin, 5-10mm from bottom) clearance is good, then good quality rings will measure good (or fit 1st over). Anyway, just trying to save bore job if possible.

Appears you done a great job on sleeve install - shame to call it fail yet
 

5twins

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If you look at the bottoms of the liners that hang out of the cylinder casting, you should find a 3 digit number stenciled on them .....

CylinderSize3.jpg


That is the fractional portion of the bore size (when it was new), as in 75.xxx mm. If you clean the piston tops, you should also find a 3 digit number stamped on them. Again, this is the fractional portion of the original size, as in 74.xxx mm .....

CleanPiston3.jpg


Subtract one from the other and you should end up with something in the .050 to .055 mm range, or about .002". Now, that was the new clearance. You'll need to measure the parts now and see what the clearance is. I think the wear limit is around .004" or .10 mm. If you find less wear than this then you can just re-ring it.

What might work in your favor is if your original liners were bigger than these new ones. That would mean they were paired up with bigger pistons and those might help compensate for any cylinder wear in your "new" liners.
 

Wingedwheel

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Old sleeves have 001 new sleeves have 017 and pistons are .956 so what is that telling me? Difference is.061 so out of tolerance? Old # would have been.045
 
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jpdevol

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The current liner's clearance to current piston -when new- theoretically produced a clearance of .061mm or .0024" that would be well within spec new. Need to see what it is now.

As a side note, the original liner and that piston, when new, would produce a clearance of .00177" that is pretty tight. Is the original liner stamped .001mm or .010mm?
 
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Wingedwheel

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I thought that was a 5 but it’s now a little smeared So I figured 7 would be close. On the other side of the state right now running the wife around looking for a new quilting machine for her so I’ll have to get measurements later. Pretty sure I was looking at .001 on the original liners. I’ll take a pic this eve when I return home.
 

GLJ

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And...boring liners only may present another set of issues
Liners need to be installed in the jug to be bored and sized. The numbers on the liners and pistons mean nothing now. That was when they were new. Now they have been ran and have worn. Take what you got somewhere that knows what they are doing and have things measured. .002 is the best piston to cylinder clearance. Over .003 and you can have problems. .005 and you can start to hear piston rattle. Piston rattle is not good.
 

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Never do shit when you’re tired. I’ve got new honing stones coming on Sunday.
 

Wingedwheel

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Liners need to be installed in the jug to be bored and sized. The numbers on the liners and pistons mean nothing now. That was when they were new. Now they have been ran and have worn. Take what you got somewhere that knows what they are doing and have things measured. .002 is the best piston to cylinder clearance. Over .003 and you can have problems. .005 and you can start to hear piston rattle. Piston rattle is not good.
That’s the plan. I just want to clean up both sets and see.
 

Wingedwheel

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Box of goodies came this weekend. I used yamahaxs650.com for my spoke sets on Patience because they were the only ones that really had any at the time(Covid issue) and this time they were only $25 ea. seem To be the same quality as the last sets so not sure why so low but I’ll take it.image.jpg
 

Wingedwheel

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What I’ve thought about doing is take a few of the rusty sets I’ve saved, clean them up and powder coat them. I can do color or chrome paint. That way I always have a set on hand…..
 

5twins

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I've been getting my spokes from XS650Direct. They have much better prices on the stainless sets than Mike's. Heck, the 16" rear sets are only about $35 ..... yes, for stainless.
 

5twins

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At the moment, they're out of 19" front disc stainless but seem to have all the rest.
 
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