Obviously it appears to be a carb issue, but if you utilize the petcock located on the fuel tank, it will normally solve the problem. Honda puts the petcock on the tank and if you read the owners manual, it will advise you to shut off the fuel whenever you are done riding. Now if you shut the petcock off and the carb still overflows, then you might have dual problems.
1) Check the petcock to make sure it stops fuel flow in the off position. Alcohol in our fuel can damage the rubber seal in the petcock.
2) A worn or damaged float needle and/or seat
3) A defective float
4) Dirt or other object preventing the float needle from seating completely
5) Float bowl drain screw not closed completely
6) Float bowl overflow stand pipe damaged (the pipe commonly splits due to vibration or moisture freezing inside the pipe) I have seen many Mickey Mouse methods of fixing the tube and almost none that work. Some people simply cap the drain. On guy actually tapped threads into the drain and put a small screw in to keep it from leaking. When the overflow pipe is damaged, I replace it with stainless steel hypodermic tubing. Honda does not sell the tube or float bowls.
Let us know what you discover the problem to be.