1976 Ironhead Sportster. On the top of the front piston is stamped a B or maybe an 8. I do not know if this engine has been worked on. Does this stamp designate an overbore size? And if so which one? Thanks in advance.

 

The normal marks on the piston top are STD [standard] or 010, 020, ... 070 representing the oversize between .010 and .070. I do not know what a B or an 8 might represent. See what others may say.

I wonder if it might be a 050 or a 060 with the rest worn down? Just a guess. You could post a pic.