air screw setting 1976KZ900

been riding this new purchase of mine a bit and it seems to be running weak compared to other 900-1000's i've owned. motor is stock,except it has a four into two aftermarket exhaust. had some sort of generic pods on it until the owner's bro put the original airbox back on. i removed the airbox filter, and it seemed to wake the bike up considerably.
the air screws are one and one quarter out from lightly seated. should i open them up and how much to use the stock air filter set up? i don't want to ride the ol' girl with no filter in place.
thanks

I believe the OEM spec is 1 3/8 turns out from lightly seated. It doesn't make a lot of difference as the air screws are not fussy.