Do I turn the mixture screw in or out to lean out the mixture on my 2004 Sportsman 600?

 

In to lean it out. Why are you wanting lean it out. The screw on the bottom of the carb only adjusts the idle mixture.

 

I don't think the screw on the bottom of the carb controls the mixture, it adjusts idle RPM. Unless the RPM's are changed by making it leaner or richer?

 

It's a carb model & runs crappy winter & spring. Put a dyno-jet kit in & it is running rich at idle. Black sooty plug & needs throttle to start warm machine.

 

The idle mixture screw is on the bottom of the carb under a brass plug that has to be drilled out. The idle speed thumb screw is accessible from the bottom of the carb also but has nothing to do with mixture and running rich.
I would start by making sure that the enrichment plunger is returning all the way in when turning the choke off. If it is not returning it allows more fuel to flow to the motor causing a rich mixture.
Also check all vent lines for blockage and check the carb boot for cracks. Checking the boot properly requires you to remove it to inspect the underside where it normaly cracks.

 

I've replaced the carb boot recently. I never thought to check the choke plunger.

 

Keep us posted on what you find with it.