The first thing I would check, is that your servos are all properly centered. If they are off a little, it could cause unequal pitch. I don`t know if IKON has this feature. But in Bavarian demon, you can make slight adjustments in the transmitter`s end point for pitch to equal it out (provided it`s only a degree or two) without changing the mid stick zero.
We really do need a little more information though, to be able to pinpoint the issue for you. But the first place I would start, is checking the servo centering.