Merc 9.9 air screw

[beckoning]

2010 Merc 9.9, single carb. 90% of my running is slow speed. The local Merc dealer said I need to lean the mixture by adjusting the "air screw" which is apparently on the intake manifold, near the carb. I want to adjust it 1/4 turn. Which way (clockwise or counterclockwise) do I turn to make the mixture a bit more LEAN?

 

[60sboater]

Turn it CW to lean.

 

[ondarvr]

I assume this is a 4 stroke, so lean probably isn't the way you want to go. (2 or 4 stroke doesn't make a difference, the adjusting is done in the same way)

​Plus it makes no difference if you know or not, just turn the screw a little one direction until it runs worse, then turn it the other way, it will start to run better...then worse, between those two spots is where you need it to be. Adjust as needed in this zone until you get the desired result. On 4 strokes slightly on the rich side will make it run better at low speeds. They're set up as lean as possibly at the factory.

​To start with you should turn it all the way in and seat the needle gently, count the turns so you know where it was in the beginning.

​