It ain't that simple. Engines is like wimmin and they don't go by common sense, no how. Too much fuel, too little fuel, foamy fuel, too much air, not enough air.

Start from zero. Close the throttle and GENTLY screw the mix needle in all the way closed (righty-tighty) and back it out 4 to 4-1/2 turns (that's the factory pre-set for the GS-40. I just looked it up). If you messed with the idle mix screw - you're on your own. Don't move one of those more than 1/8 turn at a time and only under dire circumstances.

My ST G-51 likes to start at about three turns out and then I lean it out to about 4 turns for normal running. Watch you don't flood 'em. With an electric starter it's easy to do. I stick a piece of folded over tape on the needle so I can see where it is. ST doesn't give you the option of bending a wire so you can judge turns easily.