EHP, would like to see some of your work! Some of the nerds would too! I also had to buy machining tools to learn how, and spent alot of money trying to get some things done. Usually had to wait for them to do it, at there convenience also. That's what bothered me the most, and then if things weren't right you had to start all over again. One thing I can say is I'm not a real machineist, because I've recked enough stuff to prove that, but I've improved! A better welder for sure. I have built some nice pipes for chainsaws and motorcycle saws. I do have a machineist friend that helps me on any of the technical stuff. We rebuilt our Dansco type sprockets on the 500 Honda's I have, and improved them so we have know problem going full bore into the wood. Before that we had to ease in the wood and hoped the chain didn't blow off. Those are pin sprockets, but we're working on a paddle wheel sprocket similar to the Rotex, but one piece. Sounds like your working on chainsaw motors alot. I do, but like the motorcycle stuff better. A little less modification on parts, cranks, cylinders, pistons, etc. I did build a 137cc stroker honda for Penny Halvorson, but shes been hurt for awhile now and I heard she hasn't run it much if at all. Haven't got any feed back on it.It was legal in can-alog rules but I don't know in your area. It ran a 16 tooth 3/8s in 20" wood. I might build another one for myself. Keep the posts coming and get John to take some pictures. Thanks Dennis