yeah, some bubbles are normal...the fuel will start to flow as its sucked up by your jets..
dont worry. the bubble will eventuallyclear.
if your carbs are operating correctly, and its just a bubble issue, and it REALLY bugs you...you need to burp the baby!
cut your fuel line as short as you can. secure it tightly to the carbs and then stretch it to the petcock. secure it with a clamp.
the shorter the better as it creates less space for bubbles to stick.
once hooked up, turn your PC on, and while sitting onthe bike, lean it as far to the right as you can to get gravity to aide in moving the bubbles up into your tank...and if needed, get someone to wiggle / flick / tap on the line to free the bubble. you may have some fuel out the overflow tubes tho.