Try resetting the needle back to where it should be by screwing it in until it stops and backing it out 1 1/2 turns. Start the engine and tune it until it is a steady 2-stoke pitch. Use small changes and wait a few seconds between adjustments. Once it is leaned out at max rpm, back off 2-3 clicks (richer).
Throttle down to idle for about 10-20 sec then throttle up to full. If the engine goes immediately back to full without hesitating or stopping then you are finished.
If it hesitates then increases to full, stop the engine and turn the air bleed screw in (clockwise) about 1/8 turn. Restart the engine and repeat until the throttle goes from idle to full with no (or minimal) hesitation.
If the engine dies immediately when you throttle to full, open the air bleed screw about 1/2 turn and try again.
All of this is explained in the manual.
http://manuals.hobbico.com/osm/40-46-65la-manual.pdf
Good luck