If you are running stock jetting, you can probably safely go one size smaller on the mains. WHat color are your plugs? How's the piston wash? If your plugs are black after a wide open pass, the mains can go at least a one-size smaller.
Check your jets, compare what are in your carbs with the jetting chart for your elevation and the temperature you are riding, and make sure you are at least that size.
2007 Dragon RMK 700 155", 2008 RMK 600 155", 95 Prowler 550 2-up, Really OLD AC Cheetah