Crank

I am having a problem I did a rebuild on the top end and still don’t have good compression what else can it be
 
I am having a problem I did a rebuild on the top end and still don’t have good compression what else can it be
What exactly is new? Bore? Piston? Rings?
Plus even brand new they usually need break-in before max compression. Are you actually measuring with quality gauge or just kicking it?