86-75hp Merc idles to fast

[bikerrick]

Had a mechanic try to lower idle to no no avail, I retuned the carbs so that it ran as before, it runs great and idles great but at 1000rpm. Is there something I'm missing?

 

[ondarvr]

There's an idle adjustment screw, it retards the timing, I can't imagine a mechanic not being able to slow the idle down.

 

[catfish commander]

Had a mechanic try to lower idle to no no avail, I retuned the carbs so that it ran as before, it runs great and idles great but at 1000rpm. Is there something I'm missing?

TAKE OFF ALL THE COVERS OR HOOD IF ANY AND HAVE SOMEONE ELSE THROTTLE IT. MEANWHILE LOOK AT THE MECHANISM AND HOW ITS MOVING WHILE THROTTLING UP! THEN CUT THE ENGINE OFF AND ADJUST THE SCREW LIKE ONDARVR SAID. ADJUST IT IN THE DIRECTION OF IT FOLLOWING THE DIRECTION IN WHICH THEY WERE PULLING BACK OFF THE THROTTLE TIL YOU GET THE IDLE DOWN TO WHERE YOU WANT IT...
ITS NOTHING MAJOR, BUT TAKES A HELPER SO YOU CAN SEE WHATS GOING ON IF YOU'VE NEVER DEALT WITH IT BEFORE YOURSELF HANDS ON.

 

[DavidMoore]

No Title

Unless the engine starts and idles normally but picks up idle speed as it warms up, then the carbs are irrelevant to the problem (if it does this then your over-rich).
Neither do you set the throttle position to adjust the idle.
Just like Ondarvr said for idle speed you adjust the ignition timing.

Like this
With boat in water and with throttle at idle position in fwd gear back off the screw shown in the sketch to idle about 700 rpm (I am supposing this is your engine)
It's important to do this in the water because your need the back pressure on the exhaust.

Once you did this you can fine tune the carbs, then set the timing again to get best idle.

 

[quicktach]

Change the advance setting