Why is gas leaking from my Honda Magna?

[mykd4sound]

I own a 1985 Honda Magna. It is a V-twin I do believe. Well on the V-twin part of my bike, which is black. If you are familiar with these bikes or others like it, you will know that the v-twin part has what appears to be 4 separate carberators on them. I am not sure if they are carbs, but they appear to be. On those carbs are a sort of nipple with a screw on the side of it. It appears as if those nipples are leaking gas. It is leaking from somewhere , and it appears as if it coming from them nipples. But only 2 of them are doing it. Can anyone tell me why, and how to fix it?