Rick,

Every motor is different. I have several YS's and they are all close in setup, but none are identical. You could have slight pump pressure differences or anything else, also your airflow to the carbs could be slightly different. After you change fuel if you can get the needles set and the engines are happy, just run them. I'm actually more surprised that you didn't have to adjust both, than I am that you had to adjust one,

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