Gap between head tube and fork

[Lim]

I cannot fully assemble fork into head tube. The gap is there at the down side of head tube. Is this normal?

 

[Brad R]

Yes. As long as you can tighten the headset nuts enough to remove the play, it will ride great and you will have a gap at that joint.

 

[Rampa]

It looks like something is probable upside-down in the stack to me.

 

[Vicki C.]

As the picture above shows, there is a black plastic ring or gasket that goes in the gap. I just looked at mine but then saw the photo.