Reattach the air box, it kind of works as a natural 'choke'. Its designed to restrict the air a little more and the Jets are sized to accommodate. There is too much air flowing through there for the Jets to keep up. Carbs are all about vacuum. I have been learning a great deal while working on my son's bikes. Once you try that, if you still have issues, come back and explain. You say it wont start, does it turnover or just click? Does it fire and putter out or just go ren ren ren ren? Your idle screw may need to be tightened to open the bitterfly valve a little more exposing the idle circuit of the carb. If you remove the carb you can see little tiny holes behind the starter circuit(pilot sxrew) the valve should be just slightly past the hole exposing a small out of it. If I am incorrect on this, site me please.
