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Mercury 40hp "in-gear" RPM SETTING PROCEDURE

H

Howmaster

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Hi Folks!
This is my first post so be gentle.
I have a 2002 Mercury 40hp / 2-stroke/ oil injected outboard...
and this is 2 cylinder.
on my 2002 SunTracker pontoon boat.
the motor runs great, but I want to bump up the RPM's up just
one-hundred rpm higher after its in just mugged into gear.
its idles ever so quiet in idle-(neutral)....(@850rpm)...when
just nugged into forward gear, it's (@750rpm) and is just a
little bit louder, rougher until I bump up the throttle to 850rpm
(or higher) and the extra 100rpm higher is its sweet spot. (Which I want for trolling.)
DOES ANYBODY KNOW THE CORRECT PROCEDURE TO DO THIS???
 
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Hi Folks!
This is my first post so be gentle.
I have a 2002 Mercury 40hp / 2-stroke/ oil injected outboard...
and this is a 2 cylinder. (0ne Carburetor).. And it's
on my 2002 SunTracker pontoon boat.
the motor runs great, but I want to bump up the RPM's up just
one-hundred rpm higher after its in just mugged into gear.
its idles ever so quiet in idle-(neutral)....(@850rpm)...when
just nugged into forward gear, it's (@750rpm) and is just a
little bit louder, rougher until I bump up the throttle to 850rpm
(or higher) and the extra 100rpm higher is its sweet spot. (Which I want for trolling.)
DOES ANYBODY KNOW THE CORRECT PROCEDURE TO DO THIS???
 
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It sounds like your idle is set "correctly" according to the specs - so at least it's working like it should, but I understand what you are asking to do - you just want a "faster" in-water idle because it would better suit your needs.

It's not tough to do at all - all you need is a screwdriver and a small wrench or pair of pliers.

I will post a pic below, but basically you just remove the cowl (hood), and with the help of a partner (too dangerous to do it on the water by yourself) put the motor in gear and simply back off the lock nut, turn "in" (clockwise) the idle timing screw until you get the rpms you are looking for and then re-tighten the lock nut. The screw is located on the (arm) connected to the linkage that controls the butterflies on your carb(s).

If you are looking at the front of the motor, with the hood off (so perspective of being in the back of the boat, facing rearward, looking at the engine) it will be on the left side close to the front.

Anyhow, here's the pic of what you are looking for...
 

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If you have trouble shifting into gear just set it back to spec and deal with it. Do not shift into gear slow you dont want to wear out the clutch dog if you have to force it into gear.
 
Would a different pitch prop of lesser pitch increase rpm at idle?But i would think it would affect WOT and other issues like operating efficiency,planning,ETC.
 
why not use the fast idle lever? it will give u a little bit of gas basically.. why not bump the throttle instead of fiddling with settings?
 
Ok...after looking at both sides of my motor, the parts shown on your
diagram are NOT on my 2002 Mercury 40hp with a single carburator!
this is a two cylinder with oil injection.(model # 1041412ZN)
(serial # OT571672)
 
Sorry then, I don't have a service manual covering your model.

I have the earlier 2 cylinder model book and the 3 cylinder 40's, but not the later twin that you have.
 
Here is linkage...turn the red circle d screw in 1 turn at a time till you get the RPM required....
 

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That screw is the HIGH RPM LIMIT SCREW. that's not what I'm looking for.
(when my motor comes out of a very smooth, quiet NEUTRAL posisition...
and gets bumped slightly into the FORWARD position, the RPM on my boat
tach really does change, but I can hear it's about 100 rpm lower.
At that posisition the motor runs a little rougher and a little louder.
Now, if I bump up the throttle about 100 rpm's more, that's the motors
sweet spot again and it's so smooth and quiet I can't hardly hear it run.
What I want to get to is when i (or the wife or son..) just ease it into
FORWARD GEAR, that it is at the sweet spot without idling up another
100 rpm to get it to do that. But, I don't know if it's more rpm alone or if its
a timing advance that it needs to get there!?
 
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