I don't know anything about fluid dynamics or even lectrickery
But I figure in normal setting the tap to on,the fuel flows down the long brass tube, which is about the size of one of the outlets,
So effectively straight in,straight out,
But once it's connected up,it will fill a pair of carbs, once they are full the fuel will flow through the other outlet and fill the remaining carbs,
When you go for a ride after a long time, it's always worth turning the tap on first, maybe even setting it to reserve, to ensure the carbs fill,
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