Econo,

I cannot stress this enough. Do not ride the bike without that collar. It is potentially extremely dangerous. How do I know? When I rebuilt my 28, I bought a new bearing carrier (part 3 in the diagram) because the previous owner had butchered the original. When I swapped it over, I forgot to install the collar (part 7). I rode a few hours south of Brisbane at 100kmph plus. On the way it felt a few times like the wheel was moving around. I stopped and checked every time but couldn't see anything obvious so I put it down to the wet roads. Just as I was riding into town, the back wheel fully bound and locked up. Initially I thought I had seized the engine.

The collar is designed to slide over the axle and under the seal (part 29 on the diagram you have but it is covered by the red circle) on that side of the bearing carrier. So on one side the collar butts against the outer bearing in the bearing carrier and on the other side the sprocket carrier (part 5). On the top it makes a water tight seal against the outer bearing carrier seal. It is meant to butt against the part of the bearing that rotates. Without the collar, at the very least the axle can move around or worst the inside (not the sprocket bolts) of the sprocket carrier can and eventually will bind against the outside of the bearing carrier. Obviously the bearing carrier doesn't rotate as the wheel turns while the sprocket carrier does. The collar also correctly locates the sprocket carrier to align with the counter shaft sprocket so the chain runs true.

If I were you I would buy a new one. The same part is run on the VFR400 so there are plenty available. Try a google search with the part number.

Sorry to be so blunt but I'd hate to see you go down the road and hurt yourself or the bike.

Cheers
Jim