2002 800 Edge and 550 Classic gas mileage

I have a 800 Edge and a 550 Classic both 2002. Riding on groomed trails the 800 gets about 12 miles per gallon while the 550 only gets about 8. Both are in great shape with low miles, 1800 and 750 respectively. Any thought on the big difference. The 800 is water cooled and 550 is air.

How many miles and hows the clutching?

The smaller engines work much harder to keep up. The 550 motors (or any other fan cooled motor) are jetted pretty fat, keeps them cooler on warm days.

I have an 800 rush, I ride with many other makes and models, my 800 always takes less fuel than any of the other 500's and 600's, carb or EFI.