As big blue said, ALL Kymco carbureted engines are equipped with a bystarter circuit, which functions like a "choke" mechanism did on older engines, except that it is automatic and requires no user intervention … it enriches the fuel/air mixture when the engine is cold, and after the engine has warmed up, it brings the air/fuel back to normal. You will notice faster idling for the first few minutes after it starts up; you should wait for the engine to run for 5-10 minutes before adjusting the idle speed screw. 2T engines should also have an accessible idle air/fuel mixture screw, which should NOT require any adjustment unless you've replaced parts with non-OEM parts. The idle screw should be on the piece where the throttle cable enters the carburetor; the air/fuel screw should be on the front of the carburetor, near the intake manifold.