It does not matter how many threads are showing on the outside of the carb, since you have to file that down to install them. As long as both carbs are in sync and idle the same.
^^ You can test it first, before tearing it apart ^^
But if it doesn't, loosen the lock nut, turn the phillips screw while holding the lever to the right and stop adjusting when the arrows line up, lock down the nut, double check, done.
here's pics of the arrows. first completely loosen cable at the handle bar lever. Push the actuator lever to the right with your finger, the arrows should line up.
http://bansheehq.com/forums/index.php?showtopic=114695
going to less oil is more gas, and turning the air screw out gives it more air.
Anyway, my stockish bike doesn't care between 32 or 40 to 1.
But it's always a little rich anyway.
So do you think at mile marker 55 someone changed your jets, or you burned it down?
The tapered screw with the locknut is your idle screw.
pilot jet is in the bowl next to the main.
You can switch the entire carb side to side as long as you get a longer choke hose and test your theory.
A leak down test should still first.
It's been my experience to never assume what the previous owner did was right to begin with.