i am actually planning to do rent motorcycle from SPMT and ride across South island .

i am actually planning to do rent motorcycle from SPMT and ride across South island . whats the fuel performance per litre or gallon .Plus how long can i ride a day in NZ roads before fatigue catch me to stop the bike ..I read in forums people saying best is just 2 hours of riding time a day in NZ ..I am from india and i had done 11 hours of riding here , I wish to do minimum 4 hours of riding time in NZ ..Please throw some advice about the entire trip ..