2004 Johnson 9.9 (Help)

[LoneCoyote]

Hi guys....I have a 2004 Johnson 9.9 2 stroke...When I picked it up from the guy that I bought it from I noticed that a cap covering a screw on the carb to prevent adjustment had been cut off. Can anyone tell me what that screw does ...and how to adjust it back to factory specs. Seems like the plugs are getting fairly fowled quickly and I find it kinda sluggish on the high end. The motor is like new with very few hours...plugs are new...(champion ql82c)...high test gas and mixed 50:1 with envinrude oil. Thanks in advance......

[boats.net]

That is your idle air/fuel mixture screw. This should have no effect on high speeds, only idle to low-midrange. You can start adjustments at 1 turn out.