KZ900 Carb question

Today my new to me kz900 hit the streets for the first time in 15 years or more. Still needs alot of work, needs tires bad. I need new coils the leads are rock hard,plug ends keep coming loose. i just wanted to get the pig on the road.
I have a question about 76 carbs. At the air screw there is set line in the area of 1 3/8 turns out as stated in carb settings referance . Is that what it is?? or something else
here is pic





Here is pic of bike when I got it




Todays road test



Also here is inside of tank after cleaning with viniger. i wish i had a before photo it was pretty nasty