you can turn up the idle screw and the accelerator adjustment--i had mine purposely set to shut off on my happy times engine but on my morini its not because you have to kick start it with your hand.
Well the screw is very tight. The gold one on the carb with a spring. Witch if i'm not correct is the idle screw.
Yes that's it, now try to keep it running with the throttle push in the clutch engage the pin so the clutch stays disengaged then turn the screw with the spring untill it runs by it's self. if that does not work maybe it your gas oil mix.