Welcome Kymco Owners!
Left lean, right rich. It's an air screw so imagine closing it, clockwise, turns off the air, which is richer. You want to be in the 3\4 - 1 turn out range.
Honestly, unless you ride on dirt or gravel toss I would squeeze all that oil out and run it dry. Better air flow.
how should you adjust the other screw?
wont the air screw setting depend on the setting of the other scew?
I take it the idle screw just adjusts default tension on the throttle cable ?
It actually adjusts the throttle lever on the carb by slight amounts. The tension in the throttle cable is adjusted by adjuster nuts on the cable itself.
Can someone post pictures about how to install a new jet?