RE: YS 45 inverted help
I just use Hemostats (Medical pliers or any similar) to clamp the hose while fueling, then remove them right as I am ready to start the engine--- Otherwise it will flood...Once running it should be fine...
You running a pipe or stock muffler? I had the Zen with a YS-63FZ then a Tower-75 then a Rossi-60 - great flying airplane!