I've seen on Aliexpress that a complete engine for the Stihl MS180 sells for about $27, which bring it back to my first question - if any member of the forum ever tried it? you've mentioned that you have several saw of this model in your barn, so I guess that you use them more intensively, as I wrote - I only use it every once in a while, so maybe it's worth to fix.I have several MS180 saws in my barn, they are handy saws but I wouldn't go through the effort of replacing the piston or cylinder. The cost/time balance isn't working in your favor.