here is how to tell if the screw is air or fuel:imagine cutting the carbs in half right down the middle so one half is on the engine, and the other half is on the air intake. if the screw is on the engine side of the carbs(either top or bottom) then it is a fuel screw. turn it out, and the cabrs allow more fuel to flow which will make the mixture richer.
if the screw is on the intake side of the carbs, then it is an air screw. when the screw is turned out, more air will enter the pilot circuit leaning the mixture out.
this model has fuel screws, so turning then screw out will richen the mixture. if you get to 4 turns and it is still too lean then you will need to rejet.
make sure you have the airbox and air filter installed and the system is air tight you when you adjust the fuel screw, you are being accurate.
start at 1.5 turns out, and slowly turn the screws out 1/2 turn at a time. you will hear the idle go up, and when it does, reset it back to the right idle speed. continue to turn the fuel screws out 1/2 turn at a time untill the idle does not go up anymore. after you are done turning the screws out(the idle stops going up) then turn each fuel screw BACK IN about 3/4 turn.