Marzo,

I've got two 3.2's that do not like to start after a flight after sitting for a few minutes unless they are choked again. Both are inverted installations and the position of the fuel line between the engine and the motor box could easily be creating a small vapor lock issue. Sometimes they will start and run without choking , but usually not. I found it was just a whole bunch easier to choke them every time and go fly since they always run flawlessly after starting. Could your engine be acting along the same line?