Hey guys, I'm new here so be easy on me lol. Okay, so here is my problem. This is my beater bike, and right now I'm giving it a little make over. (New fluids, new seals, new piston and rings, new brakes, new sprockets, etc.) I was just about to order a oem standard piston and rings for it, so I pulled out the piston from my junk box to make sure it wasn't oversized because I have never checked before. After close inspection and and cleaning off several years worth of carbon, I can clearly make out two numbers on the piston's head reading "05". And on the inside of the piston's skirt, it has three markings. One the read's "ART", another that read's "MADE IN JAPAN" and another reading "2T". Now I'm wondering what the ART means and the 05 means. Does 05 mean it's 0.5 over the stock bore?