Looking for small part help

[scooter]

That's a 4mm x 8mm long. looking down on the carb standing at the rear of the bike just to the right should be a plate with 2 screws. Pull one of those out and match it at home depot. Just make sure it's 8mm's long. Your test screw from the plate is about 10mm long. I just swapped them on mine to verify the threads are the same. Most all those exterior screws on that carb are the same except the length.