If the cover with the hole in it on the carb is facing the prop,jb weld or braze ,or thread a nipple in it and hook a piece of tygon to it and run it into the fuse or motor box.theres threads and pics in this forum.Most all carbs spit back some so a velocity stack will cure it also.Heres a pic of my 28cc stihl on ign.Total weight RTF minus the ign battery is 3-1/2lbs.7400 on a APC17x8.I bought this engine used also.The weight also includes the prop.