I really like the idea of some 2nd Gen owners punching holes near the neck of their tank to get more gas by getting rid of the trapped air.
While in the process of cleaning my fuel system on my 89 MKII, the punching hole technique just won't work for the MKII.
I kept saying to myself, got to "think out of the box". I kept staring at the neck of the tank, then a thought came to me. The tank already has a built in venting system at the very top of the tank. But it is connected to the overflow hose that ends near the bottom of the frame.
So as one puts more gas in the neck of the tank, the extra gas has to push the air out the overflow to the bottom of the frame. This is a very slow process
The ? is, would the extra gas in the neck push the air out faster, if the there was an air outlet above the neck of the gas tank. This I do not know.
If the answer is Yes then 2 possible solutions:
1) In the picture you can see the vent hose. Maybe one could T off from the hose and then bring the new hose section thru a hole in the square rubber unit around the gas tank neck. Then on it a valve,so that when you gas up you open the valve then close it.
2) No valve and if the gas pressure build up and over flows most of it will go down the main over flow hose and if any gets thru the T section into the square rubber unit, the square rubber unit has its overflow hose.
Any thought?
Or are the 2 levels of gas the issue? The air pressure of the gas in the neck vs the air pressure of the gas in the main tankl?