The pilot screw is set at the factory using an exhaust analyzer and may or may not be 2.5 turns open. 2.5 turns pretty much guarantees that it will run and allow proper adjustment. If you have a colortune plug then adjust as follows. Get the engine at running temperature and at idle. Close the pilot screw until you see a flicker of white (lean). Open the screw until there is no white. Install new plugs and ride the bike about 15-20 miles and pull the plugs and look at them. You are looking for a light brown or grey color on the plug enamel. If still white, open the pilot screw about the width of a dime. Continue this process until you have a nice light brown or gray color on the plugs. If you do not have a colortune plug, start with the pilot screw at about 1.5 turns and make the adjustments. I have a 4 cylinder, 4 carb Yamaha and 2.5 turns open is the standard starting point. But using the above process my pilot screws are set between 1.75 and 2.25 turns--each carb is a little different.
2004 CMX 250 C Rebel--for the fun of it
2001 Honda 750 ACE--for the long rides
2004 Honda Aero 750 (Wife)--what can I say
1985 Yamaha XJ 700--for the old times