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johnson carb question picture included

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Mexdj83

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i have a 1989 johnson 90 hp j90tlcem

This carb has two jets marked #34 and look different size. both carbs are the same way. on the parts breakdown it shows only one jet and its numbered 36. Mine are numbered 34. Is my carb from a different model and if so why do people do this. I just rebuilt my outboard and got it running pretty good.

Any help please, carb has 334327-jn stamped on it
 

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For those that don't catch it... the carburetor is pictured upside down. Those jets are idle air bleed jets, meaning they measure "air" instead of "fuel".

As such (air jets), the smaller the inside diameter, the richer the engine runs at idle. This is needed on various engines to combat a lean mixture that causes the engine to "sneeze" or "spit back" through the carburetor. Bottom line... if the engine idles as it should, leave those jets be.
 
thank you so much for the quick reply. couple of follow ups.

1. I rebuilt this engine and the starboard side cylinders were fried especially the top one. Could this have been caused by this jet setup?

2. Should i get smaller ones? I feel like it would just be safer to run rich.
3. Was the jet drilled out because they are numbered the same #34 and one is bigger than the other.

Thanks again
 
Fried cylinders all on one side.... not likely a carburetor issue. Top carb feeds top cylinders, bottom carb feeds bottom cylinders. More likely a overheating problem due to swelled blocking water deflectors, faulty thermostat, an ignition problem, something of that nature.

You'll need to get an assortment of graduated decimal drill bits and slide them in the jets to find out what size they actuall are... OR... (and preferably) purchase four new ones of whatever size belongs in there according to the parts manual and install them due to the fact that you've rebuilt the engine and are basically starting anew from scratch.
 
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