RE: Fuel mixing advice
Your problem sounds too odd for me to know the answer. I am not an expert. But have you tried the carb O-ring? Maybe there is an air-leak. Also, any loose screws/leaks elsewhere like the crankcase backplate? I am not saying that is your problem, but who knows?
I had to put a piece of fuel tubing on one of my engines' HS needle to stop an airleak there.