thought my eyes were playin tricks on me...almost looks sleeved.
That is sleeved.
From the pics of the piston & cylinder, I think the head gasket was leaking (HATE those fiber head gaskets) & washed down the cylinder (no oil between piston/cylinder) as the scuffing in the cylinder is at the exhaust port (just my $.02).
I have seen a sleeved cylinder, with no matching of the ports, and still can not understand how it runs so well, as there has to be at least 2mm mismatch in the ports, but it runs very well.
Good thing with the sleeved cylinder it can be bored for not to much monies
, add a piston kit, rod kit, crank bearings / seals & a good set of gaskets will hopefully get you riding the K5
, but I would positively make sure BOTH cylinder & head surfaces are totally flat. Had a friend with a K5 that was sleeved, kept having head gasket issues & it was just a very small area of the sleeve raised causing the problem.
DoldGuy