Yes. that is it. Need to screw it in all the way. Then screw it out about 1 1/2 turns. If you can, count how many turns it takes to screw in until it stops. Sometimes 1 turn out will do it but no more than 2. If you can, take screw all the way out (there is a o-ring and spring in there) and blow it out. O-ring is on air-mixture needle usually.
Something concerns me with the idle turned in almost all the way but don't worry about it. Maybe the needle is lower than it should be. Thats what the idle adjustment does, raises the needle. There are notches on the needle to raise or lower. But if its running fine , okay.

 

does it have stock air filter???? cuz if its aftermarket it was likely rejetted....I really think they did sometime to the carb if that clamp screw is stripped...maybe wrong jets??? have you ever had this thing running good???


it could very well be the vent hoses from the gas tank or carb...Check them all and make sure you can blow through them...i know on my quad it will run like sh*t if the gas tank hose gets kinked

change the gas too, what does the plug look like????