I bought this old Webra .91 ringed engine about four years ago, it had really soft compression, I bought a new piston, ring and sleeve and installed them. The ring never seated and it never got better than very soft mushy compression. I ordered a Frank Bowman ring and installed it and just around to running it today. I mounted what I thought was a Pro Zinger 14x6 but after 32 OZ of fuel I couldn't get more than 8,500 rpm on WildCat 5% Premium Extra with 2.6 OZ of castor added. I thought, well this ring isn't going to seat either I let it finish off the second 16 OZ tank and took it in the shop. It turns out the prop is a 14x8 and the compression is very snappy. When flipped slowly it will go over center and easily whack you finger, only once of course. It holds compression just as well as my ABN .91 which has no leak down compression. Amazing what a good ring will do. I don't seem to have a 14x6 but found a 14x7 Scimitar, more tomorrow. Incidently I'm running a 9mm SuperTigre .90 carb.