Have a full system Yoshimura RS-3 Exhaust with a no toil air filter kit on a 2007 400ex. What size jets should I be running, Main and slow. Also what is a good setting for the air/fuel screw?? this is the stock carb. I know search function is a good tool, but I want to get a straight answer.. Thanks in advance!

 

You have to also go by the altitude you are at. And the parts as well. look up your altitude on the internet and buy the stage of jet kit that best suits the mods and the quad and it should have the recommended jet for the altitude you looked up.

 

Thank you for the info! So far, I am looking into the dyno Jet kit and a no toil air filter kit. Sidenote, anyone have any luck with ceramic coating their header pipes?? Please advise. Thanks.