i just pulled a choke assembly apart. that hole/passage doesn't connect to the vacuum port of the carb or the suction side of the choke piston. i believe it to be a relief port (probably backfire relief) for the body of the choke assembly. if the assembly is carefully looked at you'll even see a small screen in the relief passage. it's supposed to be the way it is. i also think the passage could be considered a type of vent,