Vertex does make a lot of sizes for many engines, but most are not in the US catalogue, just on the one for Europe, and they won't sell it to you unless you go through the official dealer for one of those countries, which can lead to funnny situations, like the one I had a few summers ago, where the dealer had no clue about what I needed and just told him to please order the reference number I asked without any further questions. Interesting how some things work. It went from the manufacturer in Italy and their dealer to the dealer from Spain, and from there to the dealer for my area. Too many mouths to feed.Someone years ago were re-making these pistons, it might have been Vertex. You might have to put a 50mm in it and go from there. I believe you can bore them out to a 52mm. If you want to get rid of it let me know.