When I took the tank and air box off of my Africa Twin I saw the same exact design flaw, any water that enters one of the front facing air horns have nowhere to go but down towards the paper air filters, one on each side. I thought about installing some kind of drain hole at the bottom part of the unfiltered side of the air box but realized if a wall of water enters no weep hole is going to help. It appears that the front opening of the air horns are behind the front fairing so rain or splashing shouldn't be an issue, but a laydown or other submarine type of adventure would cause serious water ingestion...
Has anybody drilled weep holes in the dirty side of their air box, there must be some kind of rubber check valve that would allow water out without dirty air or water in?