# Yamaha 115 idles too,,,



## pappastratos (Oct 9, 2007)

guys, my Yamaha 115 2 stroke either idles too fast or too slow, I recently cleaned the carbs, adjusted linkages to spec according to Yamaha book. I can adjust the idle to 900 rpm, next time out it will slowly start idling slower to 500-600 rpm, adjust it up, then it will be too high. I am adjusting the correct screw according to manual. Is this common for this motor ?


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## The Maintenance Shoppe (Nov 5, 2007)

do you know how to synchronize carbs???


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## pappastratos (Oct 9, 2007)

Not sure, followed directions in book on linkages


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## Chapman5011 (Mar 7, 2013)

The Maintenance Shoppe said:


> do you know how to synchronize carbs???


I cleaned my carbs not too long ago. Put the screws exactly as they came off. I then had the same issues. I kept adjusting the screws, I had it all jacked up before long. It took a special talent to make it right. The problem was I'm not a mechanic . He was. I did the dirty work, and he took care of turning screws


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## pappastratos (Oct 9, 2007)

can you tell me how to synchronize carbs?


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## Chapman5011 (Mar 7, 2013)

pappastratos said:


> can you tell me how to synchronize carbs?


I would be willing to bet youtube.com would be awesome assistance here.


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## SHO-NUFF (May 30, 2011)

Adjust the mixture screws. Lightly seat them and back them off 1/2 to 3/4 turn is a good place to start. There are 2 on each carb. Back the idle screw off so the throttle plates are closed before you make the mixture adjustments, then set the desired idle speed.


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## pappastratos (Oct 9, 2007)

I figured that was the only adjustment other than idle speed. Book says 5/8 turn. When set like that you can hear carbs starving for fuel. I have set at 1 turn, makes it easier to start, idles a tad richer,,


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## SHO-NUFF (May 30, 2011)

pappastratos said:


> I figured that was the only adjustment other than idle speed. Book says 5/8 turn. When set like that you can hear carbs starving for fuel. I have set at 1 turn, makes it easier to start, idles a tad richer,,


 A 'Tad" rich is OK. Too rich and the engine will load up with excessive fuel and not idle worth a crap. I would run it as lean as possible. 

The best way to adjust the mixture and idle is with the foot submerged in the water so exhaust back pressure is present. You can put the foot in plastic drum cut in half, but I have had better luck putting the boat in the water and tying up at the dock, out of the way of course. 
It runs way different in the water than on a set of flush muffs.:yes:


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## pappastratos (Oct 9, 2007)

_The best way to adjust the mixture and idle is with the foot submerged in the water so exhaust back pressure is present._

Yeah, you are right. right now our area is flooded, thought I could run it in my yard yesterday!


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## Breeze (Mar 23, 2012)

pappastratos said:


> I figured that was the only adjustment other than idle speed. Book says 5/8 turn. When set like that you can hear carbs starving for fuel. I have set at 1 turn, makes it easier to start, idles a tad richer,,


Unless multi carb outboards are different than any other multi carb engine out there, adjusting mixture screws and idle is not going to synchronize the carbs. Sync'ing the carbs means making sure the butterflies all are set the same. You can do a basic " get it close " sync with a paper clip but to get it right your gonna need a manometer. The adjustment should be on the linkage connecting the carbs. That is unless these outboards are totally different with their carb linkages....


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## pappastratos (Oct 9, 2007)

_Unless multi carb outboards are different than any other multi carb engine out there, adjusting mixture screws and idle is not going to synchronize the carbs. Sync'ing the carbs means making sure the butterflies all are set the same. _


Yes, correct,


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