My mixture screws were at 2 1/2 turns. Yesterday I ran the bike at 2 turns. It seems...
Mix screws are for fine tuning. It's not a matter of setting to X amount of turns and going for a test ride. They have to be tuned by ear and feel.
Whatever the book calls for in turns is just a starting point... it's not set in stone.
The idea is to set the screws at the book value, warm the bike up and then adjust them "individually" for best idle. Some use the "dead cylinder" method, some don't. Do a search here on dead cylinder tuning.
With the bike warm and at idle, start turning the screw out. If idle drops or it starts running rough, go the other way. continue turning until rpm increases and then starts to drop again..... keep going back and forth... play with it. This will give you a better feel and "ear" for what makes a carb happy. Turning out too far and idle will drop and/or get rough... turning in too far will do the same. Once it's where the engine sounds the best, blip the throttle several times.... you're also looking for best throttle response "off idle." Me personally, I like to find highest/smoothest idle, then continue opening the screw up slightly until the revs "just start" to drop. That usually give me the smoothest idle with the crispest throttle response. I should add, once you're close, just turn a little at a time... like an 1/8th of a turn or so.
Also... keep blipping the throttle during this procedure. That helps prevent the plugs from loading up and give you a better idea of where idle will fall to on decel.
As far as the number of turns, I don't really get concerned unless I get way outside what the book calls for. For example, if it say a max of 3 turns and I get my best idle at 4, I'm OK with that. Anything past 4 though would give me reason to think about re-jetting the pilot circuit... or not, depending on my mood.
One last thing, this is an individual carb thing. If one's happy at 2 turns and the other at 3, so be it. These screws are for "fine tuning" after all... and no two carbs are the same.
Idle mix tuning is fast becoming a lost art. It's something our dads (or mentors) taught all of us old gearheads at a young age, as it was a necessary skill back in the day before fuel injection. Might take a while to get the hang of it, but it's very rewarding to be able to listen to and adjust an engine and know when it's happy.