Sid it is a conversion. Started life as an Echo CS-610 twin cylinder chainsaw. It is 61cc. Runs well. Only issue to deal with is the carb being on top so a round cowl plane would be ideal. Also thought about just turning it over and making a different exhaust. Could come right out the side or route tubes to the bottom. Too many other projects now so that will wait. Unless someone wanted to buy it of course. Here is a picture of another one I have to show you the before to go with the after. Lots of cutting and milling but it is worth it. Holes to plug for the bar oiler etc.
Tim