I have gotten 72 mpg on one trip.  I rode 223 miles on my 05, never hit reserve cause normally I do on this particular strech.  The ride consisted of about 2 hours 30 minutes super slab, and 45 minutes back roads.  This means I maintained an average speed of around 69 mph, thats about right, and I used 3.1 gallons of gas.  I about shat myself right at the gas pump when I saw this and then I hugged my little GS and flogged on down the road to my friends place. 

I routinely get around high 60's and sometimes low 70's while commuting.  the only time my mileage drops below 50 is when I putt around town and its stop and go, and I'm there before the bike really has a chance to have her morning bugs

so what should i check on my engine to help my MPG im getting about 39 MPG and thats alot of highway and crusin around 70 in 6th gear..

i think i should be checking for fouled plugs from running rich
float height check
valve shims in tolerance

anything else? and how can i sync the carbs?
also my engine is completely stock except for a K&N bolt in air filter which i put in about 1000 miles ago.
Thanks
Tim