Older 20 hp johnson af ratio question

I was wondering if anyone know

I was wondering if anyone know the factory setting for the a/f ratio. I just bought the boat and its running way rich. Anyone know how many turns on the a/f or will i have to pay a local shop $$$ to have them do it? Thanks in advance. The engine is a older 2 stroke it's white and guessing in the 70's.

"'Factory setting' for

"'Factory setting' for a 30+ years old engine might be a dream, but:
First 'decarb' Your engine using Sea Foam or engine tuner.
Check that thermostat is working, and engine reaches operating temp.
Be sure You have correct spark plugs installed, J6 if not mistaken in Your engine.

Start engine and run it to operating temp. Set idle as low as possible.
Start with mix screw 2,5 out, then slowly, 1/4 turn at the time, screw IN the mix screw until engine has the HIGHEST rpm, then back out 1/4-1/2 turn.
Check that engine does not hessitate at acceleration. If so - another 1/4 turn out.

Good luck!"