Originally Posted by Chalk Two

If from a "full" tank to "F trip" you're getting 155 miles or 250km. I would ask how many litres it takes to refill the tank.

If it's 10 or 11 litres then you're bike is, roughly, in the normal M.P.G. or litres /100km range for unaggressive riding.

The tank has a capacity of 23 litres (from full to completely empty)

If you only need those 10/11 litres, or so, to re fill at your 155 miles then you still have 12+ litres left.

This then implies your f-trip is coming on prematurely but if you're putting back in, let's say, 15 -18 (ish) litres, your bike is in the 46 - 38 m.p.g and that could be anything from riding style to poor bike health. (dirty air filter / tyre pressures / chain tension / poor engine oil grade / vehicle loading, bla, bla, bla )

From memory the 'F' light should kick in with approx 4-5 litres left in the tank giving a rough range of 60-70 (100+ Km) miles before you're pushing.