I don't and won't go by when I switch to reserve, I strictly go by mpg. And I have done mileage runs, as much of a controlled condition that I can, as per Mikuni recommendations. This way I know what the true capabilities of potential max mpg at cruise speed (65mph), and 15mph over said cruise speed, not only does the 15mph over tell me mpg, but tells me that I should be getting richer as well, and mpg should have dropped. And city? it is what it is. They put mpg stickers on new cars, they test them in controlled conditions as well, the bike is no different, it has a motor too, and there is a sweet spot for mpgs.
Yes, if you want to do a good mpg test, it can be mundane a ride, I do at least 100 miles or better and holding speed, yeah!, try holding 65mph for 150 miles without playing with the throttle, ain't fun, but it is very informative.
Any way, I don't get less than 40mpg, only once, 36mpg, but that was into a head wind, and can get as good as 49, 50mpg.
42hsr/custom air kit
, 1.875 turns screw
#98 needle 2nd groove (can even go to 1st groove, but there better not be any air leaks, or you'll never dial it in!)
take what ya can, toss the rest