Scorpion....... Your comments gave me cause to pause. I took 4 of my one Lb. fishing sinkers and weighed them on a certified scale at 4 Lb. 1 Oz. Brought them home and put them on my scale and set the zeroing knob so the scale read 4 Lb. 1 Oz. Then I weighed my Magic complete with APC Prop. a 1 Oz. spinner nut, the exhaust extension, all rubber bands, everything but the fuel. It weighed 3 Lb. 12 Oz. This is with 5, HS 225BB servos and a 4 cell AAA NiMH battery pack. I stopped at my flying buddys house this afternoon and checked out his YS 63. The Spec. sheet called out 493 grams (17.35 Oz.), on his scale it was 18 Oz. This engine would put my plane over 4 Lb. I am suspicious, did you seal your wing and fill it with helium (just kidding). Hope you are having as much fun with yours as I am with mine.
Bob C.