The main jet/shims will have little to do with mileage. I suppose if you are running 85.consistently get 40mpg.
I rebuilt the carbs and replaced the rich main jet with the oem spec so I'm a bit surprised I'm so far from spec. Is 50mpg reasonable?
Robert, if I were in your position I would verify that highway speeds are still on the pilot circuit. For instance, my bike will runabout 60-65 mph indicated @ about 1/4 inch of throttle twist. This is on flat pavement w/no noticeable headwind.Actually, since the speedo reads 10 mph high I'm probably only getting mid 30's!. I'm totally stock with no windshield. This doesn't sound right. I'm running the stock jets.
My rides tend to be foothills windy roads. I'm also 6'4" 230#. Maybe that's a factor too???