A good guide is 10 miles per litre on any of these bikes "on average" so you should expect 180+/- for your 18 litre tank, depending on how it's ridden, traffic, blatting it, etc.
My guess is your fuel gauge is giving a wrong reading if all seems okay.
My guess is your fuel gauge is giving a wrong reading if all seems okay.
More people are born because of alcohol than will ever die from it.