70mpg at best, 50mpg at worst (thrashing it) normally get 60mpg on commuting through motorway/town work over 20miles, I think it all depends on the way you ride it and when you shift up a gear, try short shifting. Also make sure you air filters clean, the fuel filters cleaned, oils changed and filter (if its a used bike), brake discs arent rubbing, or that your not holding the rear brake down with your foot (some people do this with moto X boots on and dont notice).

As for filling it up put the nozzle right the way in and fill it up until it clicks then just pull the nozzle out a bit more fill again etc etc, never really have much of a problem my self doing it.

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Plough on