pick up a 1/4 watt 250 ohm resistor...
Actually I did the mechanical adjustment way yesterday, but rode until reserve, and after pulling the sending unit, I plugged it back in and made the appropriate adjustments to get the needle where I wanted, then buttoned it all up. The only reason I ask reserve capacity is because I had to switch to reserve from a topped off tank after only a little over 200 miles and thought I was getting cruddy mpg, thinking reserve was less than a gallon.
I wacked 1/2" off the tube and my bike fills up about 6.2-6.5 when it hits reserve now. That still leaves me about a gallon of reserve.