A Rotax will always bog after a spin or when you first leave the pits, so don’t worry about that.
It can vary a bit from engine to engine, but I found that the 2nd clip position was usually best here. The way to check it is to move the needle down to 3rd position then drive on the track and see if the kart accelerates cleanly from slow corners when you roll onto the throttle to accelerate. If it chugs, it’s too rich. If it hesitates then goes, it’s too lean. Go back to the pits and move the needle clip accordingly and repeat the procedure until the kart accelerates cleanly. I always used a K98 needle.
Make sure your main jet is in the ballpark. It can vary by a jet size or so, but a 152 main during summer conditions (7700 alt dens) should work.
Charles