The top seal isn't a standard o-ring, it's a special seal, and yes there is a slit in it most likely to help it compress and seal better when the steering head nut it tightened.
If you buy an aftermarket steering head bearing kit both the top and bottom seals are included.
Originally Posted by benzine
Removed my steering head bearings for maintenance and found a rubber o-ring on top of the top bearing, it was like broken and sliced. After a quick look at it and the bearing I was asking myself; why does somebody placces a o-ring on that spot, does it suppose to be there.
I'm asking this because the edges of the bearing are to sharp for a o-ring to be there.
Can some-one tell me the contents for only the top steering head bearing?