One way to gain an extra .3 to .4 gallons of fuel in your 2.6 gallon tank is to swell the section of tank under the seat. This will increase your fuel range without changing the looks or feel of your bike.

The process is fairly simple but has some risks so be careful. To swell the fuel tank, remove the seat and leave the tank bolted down on the bike with the gas cap on. Make sure your tank is empty and flushed to prevent a fire or explosion. Apply no more than 5 psi through the vent hole on the fuel cap to help expand the tank as you heat it. Make sure you don't go over 5psi or you could damage the tank. Try blowing into the tank through the vent hose if you don't have a pressure gauge and want to limit the pressure.

When pressure is applied, use a heat gun NOT AN OPEN FLAME to slowly warm up the tank on the top down the middle until it swells to the top edge. Go slow and take your time heating the tank evenly. This is what gives you the extra capacity. If you are getting 25mpg your fuel range will increase another 7 to 10 miles with this mod.

Re-written by jschner. Original idea from KC Racing posted on ThumperTalk