If you 3w50 is the new model with the new ignitions the ajustment of the needle is

H=1 turn out
L=1.1/4 out

You have to wait that the engine take temperature for the adjustment, run the engine for 3 0r 4 minutes then make the adjust.When the engine is cold have a little lag in the transition from mid to high like lean this is normal

you can check in this link http://www.3w-modellmotoren.com/engl...toren_com.html in the seccion of engines basics settings.

Oscar Silfa