[Fot] more on piston scuffing...

[fubog1]

 Just a few other things to check.
Look at the underside of the piston for color, I like to see just a little
tan, that shows that it's getting good heat in the chamber. If is dark
brown/black, it has been too hot. That can cause the piston to run too hot and
it can scuff as a result.
Also look for a pattern, if it's scored/scuffed all the way to the top of the
pistons, it could be a ring issue, check for heavy wear in the top ring groove
(usually rich running). Or heavy burnishing/scuffing at the bottom part of the
thrust faces, likely ran out of clearance.
These long-stroke engines have a pretty high piston speed so at high revs they
are right on the edge of the limits...

 Glen