Carb Needle Adjustments For Asorted Carb Variations by Joe Reeves
these adjustment are for the older engine. 1980 and earlier, and the current small hp ob's. not for fixed jet outboards.
(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)
Initial setting is: Slow speed = seat gently(turn in clockwise), then open 1-1/2 turns(turn out counter clockwise). Do not tighten or force the slow idle needle shut or it may damage the needle.
Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in (clockwise). Wait a few seconds (10 to 15 sec) for the engine to respond. As you turn the valve in(clockwise), the rpms will increase. Lower the rpms again (turn your throttle slightly slower) to where the engine will just stay running.
Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out(turn out counter clockwise) the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.
When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.