How to tell a Scratch from a Crack in a Cylinder?

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Send it. I've seen worse on non smoker motors....I lost a circlip on a Honda motor and the pin ran the walls for a few thousand RPM's. Dug a ditch 3mm deep. Now that was a smoker!
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Bewy said:
Don't think so, too deep.
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OP is rebuilding after a previous owner already rebuilt.
The previous builder could have easily left a burr, or done other dumb stuff to the rings to cause it.

At the same time, I've seen similar when someone drags the rods and pistons out of a motor. A sharp edge can catch and cut a surprisingly deep gouge.

Also a million other things which could cause it. Keep it clean during reassembly and it probably won't cause a problem. The alternative is boring it, and if that's not in the budget then it's a moot point. Plus, plenty of half decent used engines probably have similar levels of damage and run just fine.

Heck, Porsches are known for cylinder scoring and they still make good power even with significant damage... I wouldn't lose sleep over one little racing stripe in the bore.
 
Phreakish said:
OP is rebuilding after a previous owner already rebuilt.
The previous builder could have easily left a burr, or done other dumb stuff to the rings to cause it.

At the same time, I've seen similar when someone drags the rods and pistons out of a motor. A sharp edge can catch and cut a surprisingly deep gouge.

Also a million other things which could cause it. Keep it clean during reassembly and it probably won't cause a problem. The alternative is boring it, and if that's not in the budget then it's a moot point. Plus, plenty of half decent used engines probably have similar levels of damage and run just fine.

Heck, Porsches are known for cylinder scoring and they still make good power even with significant damage... I wouldn't lose sleep over one little racing stripe in the bore.
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Even if you can feel it with your finger nail, re hone it, and go. I can't believe 2 pages on what is a simple fix. I've had those scratches in cylinder bores before. Use a white lint free thinner soaked cloth to clean up the bores from honing and your good to go. Back in the day I used cloth baby diapers for cleaning the bores, crankshaft.
 
Think trash...
That's what got in between the skirts and the cyl wall.

Run it. The ring gaps leak more than that scratch will
 
eekvonzipper said:
All Clean, Ready to Assemble. Did a Final Hone with a Flex-Hone
and Saw This Line at the Bottom of Cyl 6... (on a 273)
It is Perfectly Straight, up/down.
Ran the Stone-Hone thru it One-More-Time and it was Still There!
I can't feel it... but I don't have fingernails (just nubs)
The Flex-Hone cleans up the lines left by the Bore Gauge but not This Line.
How do I know if I should just Stop? I tried to do a Budget Build at Home w/ No Machining...

View attachment 1715923929

View attachment 1715923939
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You might want to consider getting new stones, I don't mean to sound disrespectful but that honing job doesn't look good, needs a better crosshatch pattern.
 
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