Looks like paso750 answered your questions on the bearings, but I'll also state that the bearings typically are sold as a matched set of the cage and race together. Sometimes, you can buy them separate, but it is always recommended to replace them as a set. If one part is worn and you replace the other part with a new one, it is often stated that premature failure of the new part can occur.
To remove the race (it is press-fit into the frame - similar to wheel bearings), I used a huge Phillips-head ( + ) screwdriver and drove the race and washer out from the opposite side....that is, I stuck the screwdriver through the opening at the top of the frame to drive the bottom bearing race out. As previously mentioned, you want to "walk" the race out by moving the punch (the item you are hitting to drive it out) to different spots on the race. This will also prevent the race from getting cocked to one side and getting wedged in the steering head. I typically will hit the race in this this order....
lceriani wrote:- does the seal you bought perfectly fit?
Yes, the 45 x 52 x 4 seal (junk ring) that I bought works very well with the steering head. I have not seen any signs that it will not remain in the frame and it does not appear to be rubbing where it shouldn't.
If you can find a way to safely remove the original seals, you may be able to salvage them, but I have no advice on this. I have two spare frames that still have the original seals in them, and I have yet to see if I can remove them without damaging them.
The previous owner of my bike tried to remove them and tore the seal from the metal ring section of the seal. The metal part was difficult to remove from the frame by itself. Here, you can see where I was barely able to catch the metal ring to start removing it from the frame.
I have been told that a lot of older motorcycles never had a seal, so dirt and water was able to get to the bearings fairly easily. This made replacing of the bearings more of a regular maintenance item (every few years?), but if we can prevent having to change them too often, the better!
Here is the new seal with the bearing installed under it....
Here is the new seal with the distance piece (spacer) and bearing installed....
paso750 wrote:If it`s the frame it`s better to remove the bearings. You`ll need to sand the frame or glas bead blast it and you hardly can ensure that there will be no dust getting in the bearings if you just cover them.
If you are going through the trouble to disassemble the bike, you'd probably be better off to just replace the bearings so you won't have to worry about going through the hassel of removing the forks and triple clamps to change them later if they happen to go bad.
I've known of some people to take the cage section out while leaving the race in the frame. Then, you either have to cover the races or put wheel bearing grease on them before painting. If you coat the race with bearing grease, the paint will not stick to the race and it is really easy to remove the grease and paint from it when the paint has cured. Vinyl tape, such as electrical tape, is pretty good for masking, as it is bendable and doesn't leave much of a sticky residual when you remove it.