Big4d, thanks. This came out of a troy bilt weed wacker, I got it very cheap from a neighbor who suddenly had to move overseas. Yes it does have a seperate crankcase for oil, and unlike the honda's it is in the back making it hard to get to once it is mounted on a plane. I was going to try it on a Sig Rascal 110, I just have to make some time and get the project going. It will probably fly the Rascal kind of scale like. A buddy of mine here has flown his rascal with the Honda GX-31 pretty nicely, but the Gx-31 is a much nicer better quality engine and has a tad bit more power. As far as mounting these engines inverted, I have not experimented with that as of yet, it does have a wet sump and theoretically it should operate inverted, but that does not mean it will operate efficiently for extended runs.