The inlet tube length is designed to trap air at the top of the tank to do just what the other members here are saying, so's you don't overfill. What you are discribing is the gas level dropping inside the inlet tube as the air has to escape out the vent lines, before the tank is filled up to that point, the air can escape out thru the inlet tube while you are filling it so the gas will go in as fast as the pump can pour. The air can't escape as fast thru just the vent line. To get the most gas in to a safe level, just fill it while it's on the kick stand (don't run it up the inlet tube too many times) and then you are good to go no matter how hot it gets or how fast it gets hot.
Last edited by stratowart; 10-04-2010 at 11:47 AM.
Reason: added a few more words