It is not the stock carb. The stock carb has a lever that goes over to the right side. The idle screw is on the right side, as well as the air screw. The 1988 KDX200 carb is unique in that way. A standard Keihin PWK35 has the idle, air screw and choke on the left side. Look on the Kawasaki site for the parts diagrams. You can see the difference. Look at 1988, then 1989 (or newer).
Congratulations on getting it going. Hopefully, you can get the air screw set close and live with the oddball nature.