Some could say...this is a bad rotor?

[iddqd]

I can't even find good points for a resistance test.

[sgtslag]

Try using a rubber pencil eraser (a block type, or a pencil, if you don't mind destroying its eraser...) on the copper surfaces.  It should remove the oxidation without damaging the metal beneath.  Otherwise, use a copper polish compound, with a soft cotton cloth rag.  Cheers!

[Truck]

I used extremly fine sandpaper. I've also heard of useing very fine steel wool.

[LukeM]

Sometimes, you can remove gunk with contact cleaner you can buy from Radio Shack. Should work good for copper surfaces.  Make sure you don't use the cleaner with a lubricant in it.  You just want to clean it, not oil it.  If you DO get oil on the copper, you can remove it with isopropyl alcohol.

My 2.3 cents worth.
Luke M

[iddqd]

I've heard of the eraser trick, and I've heard of the contact cleaner. Never heard of the fine sandpaper/steel wool. I'm going to try all three because if I can save my self of having to get a new rotor this season, all the better. The rotor does work fine, I manage to squeeze out a resistance test, and the stator checks out too.

[LukeM]

I recommend some new brushes, while you've got the cover off.  Chances are the old ones are gunked up as well.

Like carburetors on these bikes, the electrical stuff should be clean enough to eat off of. Make sure the copper surface is shiny clean and free of oil or debris. Glad to hear the rotor is electrically OK.

Luke M

[realjakebaker]

I have been thinking that I need a new rotor, I got a lot of different readings trying to test it with a multimeter, but the copper contacts on it were definitely not clean and shiny. It kind of works intermittently and the bike cuts out after riding for 20-30 minutes and then does not have enough charge to start up again. I will also be giving my rotor a good once over before I but a new rotor.