Two words - "Koh" and "Lipe". A cautionary tale if ever there was one.

The odometer is the gasoline-meter. Heres how you do it:
Bring a large jug or mug to pour the gasoline out. When you start, pour it into the jug, pour it back into the tank, but carefully measure how much you totally put in.
Now, my instructions said "after 3,4km".
Everyone knows that any scooter runs approx 33,33 km on one litre of fuel. So every now and then, stop, repeat the measuring-procedure and when you have spent 0,1 litre, you have gone 3,33 km.
My next instruction says 10,3 km. Measure again. My calculator says 10,3km divided by 3,33 is 3,1, so now you should have spent an additional 3,1 DL. Ok? Just do the same once in a while and youll be fine. If youre not american and measure in gallons, that is.
Or even better - write odometer in the little google-search-field up on the right and read:) Odometer is the measuring-device for distance.