the way i always did it is, start the bike up and get under it. (its easy if you put it on car ramps) then work your hand up through the frame so you can get to the screw with a screw driver. then start turning the screw untill the bike starts running a little choppy. then you turn the screw the other way untill it gets choppy again.(make sure you count the number of turns it takes inbetween the choppy marks.) then all you have to do is cut that number in half and then turn the screw. ex. say the screw turns one full turn untill the bike starts to get choppy. just cut that number in half it 1/2 turns. then just turn the screw. its kind of hard to explain but hopefully you understand. i have done it this way countless of times and it worked perfict.
-Aaron
-Aaron