my 02 grizz was pretty bad on gas in the break in process but seems to be getting better now, and is heard to get even better after the valve adjustment after the break in.

 

Sorry I can't reply concerning Yamaha ATV's, but here's some comparisons I've found in about 10 years of riding...
DS 650- about 26 mpg
400 Explorer- 23 mpg
400 Scrambler- 19 mpg
500 Sportsman- 25 mpg
250 Trailboss 4X4- 14 mpg
125 Breeze- 40-55 mpg
325 Trailboss- 30 mpg

All of these figures are what I have found on trail rides. People that ride on their own land do not rack up near the miles as on trails. You'd be hard pressed to go 50 miles in a day on your own land but 150 miles is an average day of trailriding for me. That's why people say they can ride all day on a half tank of gas. All they do is go in a circle. Mileage does go down on a 2 stroke as you rack up the miles. My 400 Scrambler is still on its original top end with about 3500 miles and only get about 15 mpg now. But hey, not all Yammies get bad gas mileage...My TW200 Dual sport gets between 60 and 70 mpg![img]i/expressions/face-icon-small-wink.gif[/img]