Off-target a bit since I have the 18 300rr, but your fuel mileage does seem kinda low. I ride 3000-6000ft. 162 main, JD red needle 3rd clip. I recently dropped from a 38 to 35 pilot because I was still spooging a decent amount. I can get 80+ miles with mix of single track & dirt roads. I think my stock tank is 2.5 gal. I ride low to mid-range RPM most of the time.