Assuming you do have a CR tank OR one built the same way..
I think the reason for the inlet being midway up on the tank was so that it would clear the frame rail (I can't remember but I think the tube swings under the frame rail then turns up).
Bad design as once gas reaches the top of the inlet tube on the tank, there's no way for the air to escape unless there a vent tube is used (which my tank does have on top of it).
That vent tube is supposed to be tied into the gas cap as seen in this pic: (Please note that the fitting for the vent tube is not screwed in, in the pic)
I suspect people just capped off the vent tube at that tank and that is why they have problems.