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86 evinrude 90 carb question

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big_jack

Contributing Member
Guys,my carbs were never rebuilt in this engine so I decided it was time. After taking them apart,(they were super clean), I noticed that one of the "Idle air Orifices" was missing. It was located on the upper left side. WoW, I am shocked.Do you think it got sucked into the engine, or was it omitted from the factory?............The motor never idled very smooth from new. Thanks alot.
 
Take a compression check. What are the individual cylinder comprssion readings? A brass jet being drawn thru the engine will score up an aluminum piston. That jet might simply be laying in the related reed valve assembly.

Running without a air bleed jet naturally allows that cylinder to be drawing excessive air resulting in one cylinder running lean.

Let us know about the compression readings.
 
Joe, Can it get past the reed valves? I will check compression tomorrow. It has been running very good at high speed for years. thanks
 
I really don't think it could get by the reeds but not absolutely sure. At least you know which reed plate it would be in. If it were me, I'd take a look.
 
Joe,I did compression checks and all 4 were around 125lbs. I got out my bore-scope and took a look into the reed valve area. Everything clean. Nothing in the reeds. I am feeling much better now. Do you loctite the idle orifices into place? Thanks for your help.
 
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