I have thought about that myself. Everything is possible, planes intended for a 1.20 fourstroke would be well suited to both a YS 1.40 FZ or a std. OS 200. The biggest problem would be torque and prop/undercarriage size. If the plane is sturdy enough, the power should not be an issue. Question is, which 90-size plane does not get the power it needs with a 90 two stroke or a YS 1.10? If you need more power than that then the plane is probably too heavy to fly properly.