[Neil E.]

Usually it's not hooked up like that. A separate hose would come off each barb and run upwards on the frame. Alternately they could be tee'd into a single hose that goes upward to vent.

I doubt hooking them together is an issue, but the float bowl does need venting so fuel will enter. You are only venting the float bowl, so all the connections are doing the same thing. Mine is teed to a single tube that goes to the top of the airbox.

Fuel out the overflow is from a float level set too high or a float needle stuck open. Sometimes you can rap on the float bowl with a screwdriver handle and get the float needle to seat.