Air/fuel ratio setting!!!!!!

[IGNORANT 2FIVE0]

I have a 2003 yz125 with pro circuit pipe and silincer, not sure what size jet is in it but i know its after market. What should I set the air/fuel ratio screw at?

[Hardtail]

There are too many factors for us to say what to set it at without knowing how it runs. Does it run good? Pop? Break up under load? ping when backing off? What does the plug look like? Let us know and we can go from there. By the way, Welcome to Mototips!