from the 2002 manual
Slow Jet And Air Screw
The air screw meters air that is mixed with fuel metered by
the slow jet. .
Turning the air screw clockwis e, enriches the mixture:
counterclockwise leans the mixture.
Turn the air screw in until it lightly seats, then back it out to
specified position.
Air screw opening: 1 turn out
After warming up the engine, connect the tachometer and
slowly turn the air screw in or out until the engine revs up
smoothly .
Adjust the idle speed by turning the throttle stop screw.
Install the jet needle into the throttl e valve.
Install the thrott le valve spring and cable setting plate onto
the carburetor top cover, then connect the throttle cable to
the throttle valve whil e compressing the throttle va lve
spring.
Installation
Install the carburetor in the reverse order of removal.
Install the throttle valve while aligning ~ groove ~h the guide
in the carbureto r body.
Idle speed: 1.300 '" 100 min" (rpm)