I just bought a 06 gs500f that was idling out at 3500. Took carb apart to clean carb and it a fresh rebuild clean as a whistle. The plugs were over the idle air screws so I know they had not been adjusted I go one out no problem it was still 4.25 out. The other plug I seriously messed up had to drilling out and damaged the screw underneath. What kind of carbs are thes and where in the world can I get another screw. A link or anything would help. The only # on the carb is 01DQ T5X6.BAL
You can use websites like bikebandit.com or partzilla.com to look at parts diagrams to help you order exactly what you need.
If you are going to replace them you might as well get the version you can turn by hand.
Factory pro makes a thumb screw to make tuning the idle circuit easier:
http://www.factorypro.com/Prod_Pages/prods11.html