Peter,

My ultimate flys VERY well with an os 120 fs on it.

I have also just bought the XYZ 26 cc (c-spec) engine from hobby city. I have not run that engine yet. Its very lightweight and seems to be pretty well machined. Other than that I cant tell you how good a motor it is.

Please note, if you do put a gasser in your biplane, it will be heavier, not just because of the engine weight, but you also need an extra battery pack and switch for the ignition.

If you do buy an engine from hobby city, be careful which one you choose. Look in thier forums (marked Customer community) and read the issues that ALL of thier cheaper gassers have had before spending your money on one.

Also, be sure to seal the covering edges of your plane really well. They use very little overlap and the covering doesn't stick as well as it should around the edges. I had to replace almost all of the hardware that came with the plane to something a little more stout. Believe it or not, with the os120 fs in it my ulitmate came out to 7 lbs 4 oz. I had to do a double take and had it checked on 2 diffrent scales. It is VERY light plane and flys like a dream. I havnt been able to get it to hover, not because of lack of power, but probably to lack of skill and I probably need to move the cg back a little to make it more stable, however after leaving the runway, i can point the nose straight up and it will just keep going. I have no doubt the os will pull it out of a hover without any trouble.

hope this helps and good luck!

Rod