The screw does adjust the idle air/fuel ratio. It will make a small difference in the way it idles but not enough to effect the cold blooded nature.It will not change the way the motor runs past 1/16 throttle position. To cure the coldblooded problem you need to change out the 40 pilot to a larger. Most guys have luck with a 45. Factory recomended is .5-.75 turns out from seated position for the screw.
Also: on the old round slide carbs the fuel mixture screw was a air bypass screw and out was lean, in was rich.
With the newer power jet style carbs it is a fuel richening screw, out is rich.
Green 06 grizzly, EPI clutch kit, hand warmers, 2"exhust cap, 26"XTRs, Power now, custom reciever hitch, 2500# Warn winch. Pro Design filter flange.