If it is running with five turns out on the high speed needle, you have an air leak somewhere. Check the carb throat/o-ring for tightness. Make sure the o-rings on the needle valves are tight. Make sure the back plate is on tight. Get rid of the idle bar plug, you do not need it and it does not do you any good, maybe some lack of performance. Check your fuel lines for cracks/holes in and out of the tank. Check for air bubbles in your lines, etc - that is a give away for an air leak in the line somewhere. Make sure everything is tight, if the head was loose, what else is loose? Just because it is a new engine does not mean that it is all snugged up tight as you found out with the loose head.

Cheers,

Chip