cleaning a starter motor

1981 kz440 D3

My starter motor doesn't want to spin when it's hot. So I bought a brush repair kit, and I'm taking the motor apart to clean it. I guess I can spray most of the pieces with engine degreaser or carb cleaner. But what's the best way to clean the armature?

I wouldn't start spraying anything. The coagulated grease can be cleaned off with a small soft brush and some mineral spirits which doesn't attack paint or melt plastic.

The armature: I think I wiped it with a soft cloth wet with mineral spirits to get gunk off. The copper armature where the brush contacts: I got some #600 sandpaper and cut a strip and wrapped it around and turned it by hand. You just want to polish it up until it's shiny.

You want to clean the gaps. Looks like metal is shorting the armature. I'd use a sharp chisel or screw driver to square them up, then use Emory cloth to clean up the bars.
Steve

Isopropyl alcohol.

Thanks guys. I wiped it down with mineral spirits, a rag, and a soft brush. I polished the commutator with 1000 grit wet/dry sandpaper. It passed the ohmmeter tests. To clean out the gaps, I think I'll use one of those tiny screwdrivers for repairing eyeglasses. Hopefully, it will leave a nice, squared groove. Not sure how to measure the groove depth, though. Service limit is 0.2 mm.

Check the bushings. Mine were shot. I had spars so I took the best parts and made one good one.
Steve

A piece of broken hacksaw blade can be used to clean between the commutator areas.