Oil filled starter motor?

1979 KZ650 D2 SR

I have zero experience with motorcycle starters, have had a car starter / lawn mower starter opened up once or twice and never seen oil in those, and have cleaned up cordless drill commutators / brushes in the past. Guessing it is not supposed to be filled with oil, and the oil got past the seal as the seal has a couple folded over spots from what looks like perhaps installing it dry.

Took it out to inspect / clean up the brushes and commutator, but it leaked a ton of oil all over, had to be a quarter of the way filled with oil.

I need to sand (or should I say emery cloth) the commutator as it looks pretty rough, and one of the brushes is shot, but I might be able to shim it for testing purposes. Bearings feel fine and spins by hand okay.

I got the motor to spin slowly if I rotated it while connected to a battery, but if not in the right sot it was just dead. The rest of the starter system seems to be working okay.

The inside of the starter motor should be dry, only a little dust from the brushes. The commutator need only a very light sanding to clean up and even the surface. Your rotor shaft seal looks damaged and let the engine oil flow into the starter body.

Scirocco wrote: The inside of the starter motor should be dry, only a little dust from the brushes. The commutator need only a very light sanding to clean up and even the surface. Your rotor shaft seal looks damaged and let the engine oil flow into the starter body.

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Okay, that’s what I thought then, I seen the damaged area's of the seal (two damaged spots) and know that is always a bad thing. Just wanted to make sure as I have zero experience with motorcycles like this, and wanted to be sure it wasn't some weird design I am unfamiliar with.

Thank you!

If there's no other damage then it just needs the oil washing out, fit a new seal, square the commutator segments on a lathe, cut back the mica between them with a small hacksaw blade , fit new brushes and you should be good to go.

If you want to see a deep dive into a KZ650 starter, take a look at this thread. You will need to scroll down pretty far on the first page to pick up the beginning of the starter refresh.

www.kzrider.com/forum/11-projects/610746...cafe-racer?start=252