I own a 81´ Special and was wondering how the gas tank is set up; there are two valves on the fuel line, one on each side of the bike. They are marked ´R, On, PR´. I assume that the ´R´ is for reserve and the ´PR´ is for primary. I´m wondering if I move both valves to ´PR´. will I then have fuel left in the reserve when I run out in the primary? I don´t have a manual for the bike...