Every time you start, stop, or turn the tank moves which meens that your gas gets shaken up preventing sediment. You would only get that if the bike stis still and does not move. adn yes the reserv and run takes from teh same gas, reserve is just a little lower.
Run a little Sea Foam every couple of tanks and you will never have a problem with water or dirt unless you put it in there or neglect.
Chad Falstad "Hawk"
2011 HD Ultra Classic "angel"
2001 Nomad 1500 Sold March 2012
2001 VN 750 "Sold June with 2008 with 21,000""Serinity"