Johnson 105Hp Commercial Model - 1999

[dav575]

I'm down here in sunny South Africa and need some advice.
The 2 above mentioned outboards on my boat run very rich. How do I go about adjusting this and get them more lean?

[boats.net]

Johnson doesn't offer a smaller main jet. Check compression is even on all cylinders and carbs are clean and bowl gaskets are good.

[dav575]

dav575

Thanks for the reply. Everything seems to be ok.
I have, however noticed what seems to be some type of adjustment screw on each bank of carburettors, situated on the left hand side of each top carburettor. It takes an Allen-key and is spring loaded. Any idea what this could be?