Re: Gas mileage wows!!
The boost bottle isn't hurting or helping you. I would leave it there.
I'm going to say that your mileage is fine. 40 in a tank is okay. The best mileage is cruising rather slow on flat land with a light bike and a jockey for a rider. Once you start playing with the throttle, going up hills, or adding accessories to your bike, your mileage will suffer. Also, these engines often run rich. All that extra fuel being burned is wasted. Getting the carb tuned could net you a few more miles and a bit more power.
66cc HT on vintage cruiser frame.
Micargi Rover with 79cc HF. The new project!