Today, servicing anything means either looking at it or replacing it. Wheel bearings, indeed, most bearings are sealed for life now and can't be serviced.
I had a 1928 Chev buckboard ute. The wheel bearings were ball bearings in a captive race. I had a BA series Falcon ute ...to my amazement the front hub bearings were ball bearings in a captive race (nothing is new under the sun). In between the two...nearly every wheel bearing I ever saw was a tapered roller bearing.
MOST of the bearings (Swing arm, Wheel, para lever, Steering head) in airheads are tapered roller bearings. They are quality items and are, by an large adjustable and serviceable. Some of the later airheads have sealed wheel bearings but most have Tapered rollers.
On the /5 and /6 models particularly, the set up and pre-load of the wheel bearings (particularly the rear ones) is a bit tricky and unique. I won't go into the nitty gritty of the set up here but suffice it to say that bearing pre load that isn't set up properly or wheel bearings that fail due to lack of maintenance or incorrect set up can ruin an alloy hub completely. These aren't so easy to get any more and are costly to make good (if indeed they can be made good)
The good news is that once they are set up correctly and if they are kept greased and the seals are in good order, these tapered roller bearings will go many many thousands of kilometers with total relaibility and NO damage or wear to the hub.
I changed the front tyre on my 75 /6 today and took the opportunity to service the front wheel bearings in the process. The /6 has a heavy chromed seal housing and the internal pre load tubes including the "wedding band" which varies in thickness but doesn't need to be touched once set up and until the bearings are replaced. I did the rear one (which has a blind side on the /5 and /6 and requires some stuffing around to do) last time I changed the rear tyre (about 5K klms ago). This process requires heating the rear hub to remove the bearing and pre load stack and is a PITA.
If you own a /5 or a /6 (and indeed a /7 up to 1983) don't ignore the wheel and swing arm bearings. They need to be serviced every few years.
In the pic on the top left you can clearly see the main pre-load spacer in the center of the hub. The "wedding band" adjustable spacer is on the other side.You can see the outer race quite clearly. The pic on the top right shows the chrome seal housing used on the /6 models the inner race and the "top hat" spacer which goes up against the inner race and through the seal to make it possible to set the pre load on the bearings. The pic on the bottom left shows the back of the back side of the seal housing. The last pic on the bottom right shows the bearing assembly cleaned and repacked with grease ready for the seal housing and top hat spacer to be re installed ready for another three years or so of trouble free riding.