So I'm guessing this isn't the stock carb since it's super clean and doesn't have the infamous "D" shaped air/fuel screw. Problem is, I've been having trouble with my atv running lean (no airbox and coreless stock muffler) so I put on a new filter and plug but this seemed to make the issue worse. It has trouble holding idle and every few seconds it pops like a misfire, plus it pops a lot on down rpms. I decided to mess with the air/fuel screw to see if I could make it better. I turned it in until it started to choke, then started backing out until it idled good but no matter how far out I turn it the poppin from the down rpms never stops though it does get slightly better. I'm thinking maybe something else needs to be tuned but I'm not sure what number one and three are? Also the screw gets so loose after about a turn out that the vibrations just make it turn, could I solve this with loctite?