CR400 piston question

Good info. This one is all non-reed 72-74. Aluminum cases, clutch lug on right. Yes, bore looks horrible in the photo, looks great in person. It does look like the ring pin would be right in the middle of the left intake port. I'm gonna have to look at that. Every non-reed piston photo I've seen has one centered intake window, and the ring pin just to the left of that. Sure runs well.