Drizzle gas into tank
After riding for 5 years I just figured out how to get that last 2 quarts into my gas tank.
Usually when you fill your tank the pump runs till the level is a few inches below the tank opening, then it kicks off. Then if you try to squeeze the handle just a bit to slowly fill the rest of the tank, you squeeze the handle and it turns on suddenly with full pressure. Once you have the lever on you can back it off and slow down the flow, but that initial click shoots gas back out of the tank.
So: hold the nozzle and lever with one hand, and put the thumb of your other hand on the back side of the lever. Now when you squeeze the lever on to start the pump flowing, your other hand stops it from snapping on full, and you can get the pump to click on slow from the start, and drizzle the last few quarts into the tank.
Try it when you first start filling the empty tank to get a feel for it. That is how gas pump handles should work.