Carb question, screw

[Guest]

I have a 78 gs750 original carbs.
what is the screw under the carb, next to
the float bowl and what is it function?

[Steve]

That is the "pilot fuel adjustment screw".

Its function is to control how much fuel is admitted to the air stream at idle and very low throttle openings.

It is teamed with the "pilot air adjustment screw" on the side of the carb intake, which controls the amount of air that is mixed into the pilot mixture.

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[kennerth750]

Ok, the reason I ask is because my nephew "helped" by unscrewing all four....
is there a "goto" sorta setting for them?

[Steve]

What modifications are there in the intake and exhaust systems?

For stock, about 3/4 to 7/8 turn out from LIGHTLY seated should work just fine. If you have pods and/or a pipe, 7/8 to 1 full turn will probably work.

As a starting point, the air screws on the sides should be about double the fuel screw settings. Turning the air screws IN (clockwise) will richen the pilot mixture, turning them OUT will, of course, lean the mixture. Adjust that for best idle and response when the throttle is 'blipped'.

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