The only one I know of or that has been referenced here is an Echo CST-610 and it is 61cc. I looked for well over a year for one and bought the whole chainsaw off of Ebay. Runs like new and didn't do anything with it. Then I found a bunch of them and bought those from two different places. Converted one and it is very strong running with a Falkon ignition. The engine will work best on a round cowl plane or a big warbird. The carb is on top. I am looking at the others for a way to rotate the cylinders but I don't like what I see. I may just rotate the engine itself and have the exhaust on top and make a custom exhaust for it. I am looking at the Aviation Models Yak 54. If you take your time and look around you can find them. As it sits it turns about 7400 with a 3W 20/8 prop. I think I will end up with a 24/8 or 10 and will be turning 6800 or so I hope. BME used to make the engine and had a case made for it. D&B Engines still does and makes a case for it too. About $1000.00 for it. Here are pictures of mine.