You need to do fall away adjusting, here is a quick definition taken from a Harley forum.

Google FALL AWAY STEERING ADJUSTMENT for a more detailed explanation.

Fall off is the method used to adjust the steering head bearing preload.

It's covered in just about every manual for the model specific bikes.

Once you have lifted the bike off the ground and level, the fall off is the swing of the front wheel from each side to center position and the return of the wheel to a stationary marker that is placed in the center of the front fender for a reference pointer.

The front wheel is turned to the side and should cross over the center point and return to it with a pre determined amount of swings, usually one full swing past the stationary marker and a partial return swing.

Adjustment of the fall off is done by tightening or loosening the steering head nut so once the front end is swung to the side that it returns to the middle after noting the amount of swings and adjusting the steering head nut looser for more swings or a bit more snug for less of a swing.

As usual, you should have the factory manual for the proper procedure and specs to perform this adjustment. If you are not sure of your capabilities to do this procedure, it's best left to a professional.