I was reading about your engine problem. But first I must say you did an excellent job on the plane. I was wondering if when you are inverted if fuel is flooding back on the carb overflow/return line. I did some reading on this since there has been some question about the function of the return line. Honda says that it is a overflow/return line and does not pressurize the tank. If you assembled the tank in the classic manner, when inverted the weight of the fuel on the return vent may restrict the return and flood the engine. Also, did you run the return line back to the tank, is your tank vented? Your high speed starvation sounds like you didn't vent the tank. Something to check...

Gis

[quote] the only "issue" I noticed, was that the engine didn't want to run inverted.