The low fuel warning lights are not the most accurate in the world,so I dont believe you can guage fuel consumption on the amount of miles ridden before it lights up.The easiest way is to work out yer MPG.We all know that its effected by types of roads/conditions/throttle openings/etc.
My GenII does an average of 30mpg,and thats on twisty B roads and fast A roads.I fill up when the fuel light comes on,and make a mental note of the mileage.(Usually around 90) Normally,I get just over 13 ltrs in there.Yesterday,we went over to Silverstone and I got 40mpg.The route is very boring,...mainly dual carriageway. We kept the speeds down as the traffic was heavy and the Police everywhere.(70-80mph)I filled up with 105 miles on the clock,(no fuel light lit) and the tank took just over 11ltrs.
Alledgedly the GenII tank holds 18ltrs,....I've never got any more than 15 in there.
Oh,gearing?I've got a 15t on the front and the standard 40 on the rear.