Your tank should hold 4 US gallons of fuel, when the fuel light comes on you will have used 3 of them and have 1 left, when this happens and you are riding, it will interupt the fuel pump relay and you will begin to notice a sharp drop in performance as you run the fuel out of the carbs, when you switch over to reserve you are only bypassing the fuel interrupt circuit and turning the pump back on, if you don't refuel, the bike will keep going until you suck the tank dry, at this point you will have approx 140 or so miles on a full tank................Tom.
