I would highly recommend just ripping out all the emissions junk, it's tacked on after the bike was designed for us EPA emissions. Your bike will be faster and run better in all conditions without that cr*p on there. Because EPA says you cant have one bit of gas venting to atmosphere, there is no vent on the gas cap, it is required to vent into the charcoal canister and eventually be fed back into the intake. It is not illegal for an individual to remove this stuff, just has to be there to be legally imported and sold the USA (California screwed us all over). I don't know of a way to clean it, because I always just remove if there are any issues. You can just take the vent hose off the gas can and leave the rest of the emissions stuff if you like.