I don't really know, probably something 80cc or larger, and be able to run (somewhat easily) a stihl mount bar. The greater the basket case, the better. Again, I need to get rid a saw (Mac 250) before I get another. Problem is that I probably can't sell it for a decent price until I get it running correctly. It has a new carb kit, air filter, duckbill valve, and is converted to run a modern stihl mount bar. Right there, that is around $100 is parts alone. Still pretty sure it's a carb issue, but it's hard to fix it with the little time I get when I go home. Despite that, I could probably work a new saw into the mix if I was able to sell some of the elm slabs I milled up some time ago to cover the cost.