Dual needle carbs such as that engine has, the idle needle can take over high speed control. When that nappens, nothing will work correctly.

Basic setting for the idle needle:
Back it out 5 or 6 turns.
Close the main carb barrel (servo control)
Carefully turn n the idle needle until it either has resistance or moves the carb barrel (watch carefully)
Open the idle needle 2 turns. That will be a sloppy rich idle.

Close the main nedle and open it to 2 1/2 turns.

NOW, start the engine at 1/3 to 2/3 throttle.
Adjust high speed with the main needle. DON'T touch the idle needle unless the high speed is set.

Slowly reduce throttle and adjust the ile needle very gradually. 2 clicks (*1/8 turn) at a time maximum. You are looking for the engine to run smoothly at as low a speed as pssible. The best adjustment will have a stable idle with the carb barely cracked open. (main barrel) The engine should be able to sit at idle for 20 sec, then you slap the throttle to full and it will hesitate less than 1/2 sec before responding.