Every bike fuel mileage depends on following conditions:
bike tuning, air filter, oil filter, fuel filter, oil change period.
It also depends on riders and surroundings too for example what kind of weather, temprature of city, at what speed you are riding, which kind of road, How much gentle you are with accelerating and Pavilion riding or single?
in simple words take care of your bike do all the stuff like tuning change oil when needed. change filters if they needed and drive in economy zone. I assure you 90% you will get best maximum output from your bike. -10% in case of some technical problem with engine or some specific engine part.