I also did a mm reading and it was 50.15mm. But I was pretty sure it wasn't stock, must be wrong there. Thanks Jack

 

Top of Piston is stamped 0.5. So I guess it's .5 over and my cylinder measurement must be off? Also on the bottom of the lower cyl fin is etched "YZOTIS" . attached are pictures of that. Lt80 does this mean anything?

 

NO. That's for me.. lol

 

Was able to bead hone and add new rings and gaskets. LT80 Running good again. Grandkids are happy.