Thumbscrew style A/F mixture screw

[CaptDanbo]

Well, I tried out this thumbscrew style air/fuel mixture screw from factory pro. I can't seem to get rid of my low end throttle stumbling. Mid range and full throttle seem fine and the bike pulls hard after I get moving. But from a stand still, it burps and sputters like crazy. I've tried 3 different pilot jets with no change. I tried the stock 55, a 58 and finally a 65. Nothing seems to help. I'm wondering if anyone else has tried this type of A/F screw and if they had any problems with it. The problem goes away when I choke it a bit and I definitely don't have any vacuum leaks. My X is running with a Hypercharger and HK slip on pipes. I'll probably pull the carb down tomorrow and re-install the original A/F mixture screw and see what happens.

[Tuco]

so it was running fine before the new fuel screw?

Are you sure you set it at the same amount of turns out the OEM screw was set at?

[BLKTRO]

I have FactoryPro A/F thumb screw and have no problem with it, i don't even have to choke the bike. i have aeromach UltraFlow and V&H cruzers exhaust, 195 main and 65 slow 2 1/4 turn on A/F mixture.