i also have a us 41 i fly mine with a zinger 18x8 it seems happy with it your plane may differ, the 41 does need some break in time bolt it to a stand and try to run a gallon or two of fuel through it before putting it in the plane i recommend using only a good synthetic oil in it ,zenoah , amsoil , or klotz are all fine , i would recommend mixing it at 4 ounces to one gallon on a new engine and after break in period reduce it to 3 ounces per gallon from then on , good luck and have fun with it