Personally, although there is a power increase, I wouldn't take apart a good running 290 for an upgrade. I also would not build up a 290 without upgrading it if I needed to do engine work. I usually upgrade saws that have scored pistons. Often times the cylinders can be salvaged and a new piston could fix it but I don't bother. Thus I have a supply of 029 cylinders.... On most of this series saw, when I get in a non runner, I completely disassemble the entire saw and clean all the parts and put them in the appropriate bins. When I build these saws up, I do it in stages and it would be possible for a saw to have parts from half a dozen different ones. I try to use all nice parts on one saw and all ratty parts on another and then price them accordingly. I change out any badly worn parts and stock most items for this model so I have a supply of items to draw from. I usually reuse the Stihl fuel lines as the aftermarket ones don't work very well. (only about half don't have issues) Most everything else I inspect and if it's good I reuse it, if it's not I deep six it and get a new one or another used one. Right now I have a bunch of built up engines in engine housings but don't have enough good plastic to complete saws. I'll just wait until some more parts saws come along. My next project is going to be building up some 1123 series saws which are similar but smaller. I haven't done many of those yet but have parts gathered up to complete a half dozen of them. (that's the 021, MS210, MS230, MS250, 025, etc.) I also have some MS460 and MS660 saws to do. I'd like to get some of those done before the May 30 Georgia GTG but just don't know when I'll have a chance. Grass is growing, stuff needs fixing and saws are pretty far down the priority list.
