Rotor taper and mystery seal

[Dogma]

About 2000 miles ago I replaced my starter clutch. Last weekend, on the way home, I thought I sheared the starter clutch mount screws again, somewhere near Cleveland. It turns out it was the rotor coming loose from the crank. Four hours from home. Good thing she's reasonably well tuned and bump starts easily.

The crank's taper now has ridges that don't quite catch a fingernail. I'm looking for input on whether to worry about that and best practice for installation.

The other question has to do with what I've circled in red. That's the broken end of a thin rubber thing that circled the bearing. It's not on the parts diagrams, so I think it's part of the bearing assembly itself. The pieces that came off were thin, just enough material to get around the corner of the ID to the face. Does anybody know what this is? I couldn't figure out any function for it. I'm thinking I should tear the rest of it off and forget it.

[TeamDar]

The seal and varnish colored metal are one piece. It is separate from the bearing. It is item 23 on both the 1000G and 850G parts diagram. Part number 09289-48002.

[Dogma]

Aha! Thank you. My first mistake was looking at the bearing in the middle of the crank on the diagram, as if it was the end of the crank. Oops. I see now what it seals on the back of the gear. I'm still not clear why it needs to seal there, but I'll trust Suzuki on that.