To answer a couple of questions that weren't answered, the screws that you have identified in the picture, number 3 is the float bowl drain screw, so ensure that it is tight, as mini bikes rule stated. Number 1 in that picture is your idle adjustment screw, and set that as required. Number 2 in that picture is your fuel screw and is usually set between 2 - 2.5 full turns out with correct jetting.
Also, if you are still having the problem of fuel flowing out the overflow tubes after you have checked that screw number 3 is tight, you will have a stuck float, and will have to take the float bowl off, check the needle and seat is in good condition, and just ensure that the float is no longer sticking.
Also, if you are still having the problem of fuel flowing out the overflow tubes after you have checked that screw number 3 is tight, you will have a stuck float, and will have to take the float bowl off, check the needle and seat is in good condition, and just ensure that the float is no longer sticking.