I usually let mine run out of fuel before I refill it. I do keep an eye on the fuel level though and once it's close to empty I take it easy as I don't want that last second leaning to occur when the engine is working hard at high rpms. At least one good thing about the side-mounted Savage tank and pink fuel, it's easy to see the fuel level during a drive-by.

As far as refueling, the engine won't lean out when you open the fuel tank as there is basically no exhaust pressure at idle that would pressurize the tank anyway. The tank pressurizes as the rpm's go up.

I see the racing crowd (buggies in particular) come in for pit stops and many used a force-feed fuel gun that refills the tank in a couple of seconds.