when you adjust the mixture screws out and the bike revs up, its telling you it wants to be richer. Adjust the speed stop screw down, and keep richening up the idle mixture until you find the spot that making it richer, or leaner, makes the idle drop. The bike is very lean at the point you are now, so when you turn the screws out, it gets happier and revs up. my xs is set at roughly 5 turns out. im actually going to put bigger pilot jets in it, and try to get the part throttle lean surge out, but still be able to idle nice.