In and Out Idle Mixture Screw

[Wheelman-111]

Greetings:

I've heard this called the "Air Screw" a lot, perhaps incorrectly.

Which direction is Lean/Rich. In/Out?

Since ithe tip is in a fuel passage, I'm thinking if you block that passage by turning the screw clockwise and in, you lean the mixture. Opening it up (counter-CW and out) you add fuel, thus rich. Am I correct?

[losthope]

clockwise is rich counter clock wise is lean.

[scooternewby]

clockwise is rich counter clock wise is lean.

Really? huh, i did not know that! Its a good thing to know!

[Wheelman-111]

Greetings:

Thanks for the response. Can you explain it to me?

[losthope]

maybe. when you look into the carb from the filter side you will see a couple of holes. one of the holes is the hole for the air for your idle mixture.if you look in that hole with a flashlight you will see the tip of the mixture screw. so the mixture screw blocks this hole hence turning the screw in restricts air making it richer. as far as i know the fuel flow at idle is a constant amount with no way of adjusting it. it just flows up the brass tube from the bowl and into the carb. the passage ways are pretty easy to trace with the bowl off the carb looking at the bottom at the casting.

[Wheelman-111]

Greetings:

Good explanation! I understand now. I will pay attention next time I have carb off. Might learn somethin'.

[Kenny_McCormic]

Greetings:

Good explanation! I understand now. I will pay attention next time I have carb off. Might learn somethin'.

might, yea the actual pilot/idle jet is fixed and richer than it needs to be the air screw leans it out with air.