flyjoe; The saw just had a decal on the side, 2.3/16 . I had a heck of a time trying to figure that out. But I ran across a place out of Maryland ,when I sent pics, said it was an old poulan micro 25 but im not sure what cc it is. My Gee bee I figure with engine will weigh about 14lbs . If this motor is a 25, It wont be enough? I had an 1/3 eagle before, with a quadra 35 and it flew nice,but lacked the pulling power. So I know it will need at least a 45. I have just finished a TF 47with flaps, maybe the 25 would be better in it ? thanks, Al