This is from the Saito booklet in the box Saito 40a    From the prop hub face to the center  of the front mounting holes    dimension H-   46mm (1.8110").     mounting hole front to back on center  dimension B-   15mm (.5905").  Mounting hole patern width on center   dimension A-  38mm (1.4965") Crankcase width (width between engine mount bearers    dimension G-31mm(1.2205") I might be off on the conversions just an RCH, I hope that helps.