This definitely isn't scientific either. 2002 kx250 2.2 gal, 2008 kx250f 1.9 gal, 2009 kx250f 2.1 gal. I looked the 250's up because they are primarily designed for one reason, motocross, unlike the 500's, with huge tanks, that got used for everything except motocross. So I'm thinking Kawasaki designed the 250's to go about the same distance on a tank of fuel....30min +2 laps. It's just a thought. JFAB