AFR and chain - get them checked at SVC
Air - better fill Nitrogen... its good and pressure lose is less. I've only filled N2 in ma ride, and that too only 4 times in 6 months...

Riding style - I cannot comment on that... coz whatever way i ride, my mileage doesnt drop below 38... and I dont think you ride in such a way as to affect mileage so badly...
finally..... dont worry too much... machines malfunction all the time... its just a matter of tightening the right bolt






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