Most easiest way is by the sound the bike makes on shut down.
phfft    no
KERPOW    yes

Now a blue header means it's a little lean at your normal cruzin' rpm.
Unless you cruze at idle you're gonna have to bump the main up a little.

vers... most times on shut down it gives one medium sized fart but sometimes it draws attention...a little louder.

Danger!, danger!,.. No bottom!...

The brass plug is about an 1/8" thick... and when you get through it, you will leap to the idle mix screw head and butcher it up...

Use a sharp bit, and go very slow... the brass cuts like butter, and if you catch it right, the bit will snag and let you pull the plug out...
Do not push... you will go past and mess up the head of the mix screw... as soon as you feel the bit start to bite, gently pull instead of push and the plug will usually draw right out...
Slow, and easy does it...

I know I sound like a stuck record but.....

maybe make sure it needs adjusting before you drill the plug.
On my 07 I did the 1/2 spacer mod only, and I never had anything run so perfect.

IMO, (and minimal exp) if it has a good idle, it don't need adjusting.

If you are nitpickin at pops and sneezing at shutdown, I don't know if the air screw would change that.  

good info guys. i was thinking that because my pipe is blue i may be running lean though. i will be changing the spark plug next weekend so i'll check on it. the bike fire at shutdown is not too bad but engine braking in 2nd and third gear sounds pretty ridiculous i think....like four or five backfires each time unless i let off the throttle super slow.

  The inside of your muffler knows if your lean or rich,Black rich,Gray lean,Stick your finger in the muffler(When it not hot) and rub it around see what comes out on your finger.

The only way to really "know" is by using an exhaust gas analyzer. Everything else is no more than guesswork or "rule of thumb." It is entirely possible, and in fact likely, that the mixture is lean at some settings and rich at others. For performance, it is very usual for the mixture to go rich at wide-open throttle. For economy the mixture needs to be leaner at cruise. When you add the EPA you get leaner mixtures for emission control. The mixture changes from day to day as the barometric pressure and the ambient temperature changes. The mixture changes with different fuels as the refiners switch from winter to summer blends. The best you can do is strike a happy medium where the settings is "pretty much right" most of the time. Unless you want to go to the extremes like racers, and rejet the carburetor for every day's ride.