Double check your float needle setup. the spring should be fitted into float hinge area and not sitting on top of it as it needs to pull the needle off the seat area as the float drops. This might be the cause of the leaning of the engine as fuel flow would be too low in the carburetor for the main jet to work properly.
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As the second hole it might be something that are using a different setup and just not finish here as it is not needed.