Hi guys, I’m new to the forum and have a few questions to start off with. I have a 1972 Yamaha R5 350. My dad was the original owner and this was the bike I learned how to ride on. I have a lot of 2 stroke experience but stopped riding when I stopped road racing back in the early 90s so I need my memory to be jarred. I just took the heads off my R5 expecting to find .25, .50, .75 or 1.00 stamped on top of the pistons. What I found was .040. Can anyone tell me what size this is? 1st, 2nd, 3rd over? And what ring size I need to re-ring them? The engine is free and cylinders have very minimal scoring. Also, if I remember correctly, RD 350 cylinders will directly slip onto the R5 bottom end. CAN somebody confirm this for me. I appreciate any help I can get with this.