I took the choke off and just used my finger (pinky) through the front hole in the cowl... Don't know how well that rubber button will hold up to gasoline... the boxers spit a lot of fuel out the carb when run on glow fuel, on gas that should be reduced quite a bit... I don't know what that button is made of, but its not silicone, possibly soft vinyl.

On the Gauil I replaced the carb 5mm steel socket head mounting screws with 5mm nylon screws, and a 1/4" silicone rubber insulator between the mounting flange and carb base.

If I were to run the os boxer on gasoline, I'd make a modification to the intake runners... I would cut the runners off about 5/16" - 3/8" behind the tube nut... leaving a stub and then use a rubber coupler to re-join the intake runners back onto the end of the stub... leaving a small gap between the ends of the of the cut tube... to thermally isolate the intake runners completely from the cylinder head.