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95 mercury 115 4cyl 2 stroke

H

Harelymike

New member
Just purchased this motor. This is the one that runs on 2 cylinders under 2000 rpm.
It kicks into 4 cylinder mode going onto plane very nicely and purrs along great.
But when I come of plane and drop below the 2000 rpm it can run very poorly for a couple min.
Is this normal. I have read they idle terrible.

Mike
 
They do not idle terrible. They actually idle very smooth when they are right. Since it is happening at an idle look at the top 2 carbs could have dirty idle circuits. Look at all the linkages make sure they are all in good shape.
 
flyingscott said:
They do not idle terrible. They actually idle very smooth when they are right. Since it is happening at an idle look at the top 2 carbs could have dirty idle circuits. Look at all the linkages make sure they are all in good shape.
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Let me clear it up a bit. It does idle well, but when i come down to idle, off plane it stumbles for a bit then runs fine.
Its that stumble that has me concerned. It shakes and rattles then runs fine.

MIke
 
Have the same 2+2 motor with the same symptoms. I'm thinking it might be taking time to burn the accumulated fuel from the bottom 2 cylinders once you get below 1800 rpm. After about 10 seconds, the motor is absolutely smooth. I intend to recheck the float level on the bottom 2 carbs. If I tilt the motor up a little it seems to help the transition...that's why I suspect the float level. Linkage is synched to factory specs.
 
bobbyc said:
Have the same 2+2 motor with the same symptoms. I'm thinking it might be taking time to burn the accumulated fuel from the bottom 2 cylinders once you get below 1800 rpm. After about 10 seconds, the motor is absolutely smooth. I intend to recheck the float level on the bottom 2 carbs. If I tilt the motor up a little it seems to help the transition...that's why I suspect the float level. Linkage is synched to factory specs.
Click to expand...


I will play around today. Maybe coming off plane at a slower rate will be better. Less fuel moving through the carbs when they shut down.

Mike
 
Harelymike said:
I will play around today. Maybe coming off plane at a slower rate will be better. Less fuel moving through the carbs when they shut down.

Mike
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Tried coming off plane a little slower and it seems to be getting better. I also put in some cleaner conditioner, and that might be helping out as it goes through more gas.
I am going to get some carb cleaner next
 
I talked to a mechanic and an owner of another mercury dealer. They both said normal. They are a finicky motor and are hard to set up properly. They both figure its a little gas left in the cylinders after dropping below 2000 rpm and its trying to fire. It does go away after 30 seconds and sometimes it does it less than others or not at all. Other than that it runs perfectly. I have added a cleaner conditioner to the gas and seems a bit better. I purrs along nice over 2000 rpm.
Plugs are brand new.
 
Have the same engine but a 1997, it does the same thing after running fast and slow down the motor shakes then clears out. Do you have the oil injection hooked up, I have the injection hooked up , however I have heard horror stories if the motor should over heat, I understand it will kill the oil injection!
 
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