I have a friend with an early 90s model Honda fourtrax 300, just rebuilt the carb and got the thing to run but only with the choke on. So I went to adjust the carb and I can't find anything even resembiling fuel or air screws. The only adjustment I can find is a screw surrounded by a spring with a plastic **** on the bottom where you grab and twist it, but this only adjusts the idle speed (screw regulates how far the throttle is allowed to close). Am I insane, blind, or what. Someone please enlighten me how to get this thing running right!

 

Its on the bottom side of the carb, in front of the float bowl.
If the screw is at 2 turns out or so, check the pilot jet for being plugged up.