139qmb gy6 50cc engine idle screw not changing anything

Hi there, I have an sym 50cc 4 stroke with a 139qmb gy6 engine.

Im trying to get it running right cause the first time I took it out it was that slow I was over taken by a push bike. Since then I've had it around 30mph and its running better but still not perfect. The air filter was completely removed when I got it so I fitted a foam one and cleaned the carb out.

I've gone to a 90 main jet and it still has a 35 pilot jet but when I try to move the air mixture screw it hardly makes any difference. Does this indicate that my pilot jet is too big? I have unwound the idle screw so that isn't affecting my idle and I have slack on the cable. I have zero air leaks aswell having already replaced an o ring under the inlet pipe.