If you look into the back of a vintage Flyer/Rep/TT/Sprint crankcase, there is usually a letter stamped on the rear edge of each crank chamber. I have seen lots of ‘R’s and a few ‘F’s. I used to assume that ‘R’ meant RZ or RY for TT Rep type engines, and if it is an ‘F’ it was for a cooking model Flying Squirrel. Now I am not sure what the stamping stood for, or why it was done, because I have a short-stroke Flyer engine with ‘R’s stamped in it….
Has anyone out there any other ideas ?