The first screw looks like a the lid on a toothpaste tube, and is the idle speed adjustment screw. The factory setting for this screw is 1.25 turns out.
The second screw is the air/fuel mixture adjustment screw, and it is recessed at an angle next to the idle speed adjustment screw. The factory setting for this screw is 2.5 turns out.
Experimenting with these screws may yield better or worse performance, depending on other modifications you've made to your scooter. For most riders, the factory settings should be kept.
Thanks to Speedy for his input.
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