Starter motor commutator refurb the cheap 'n' easy way

[mollusc]

More often than not, your starter motor issues will be related to the brushes wearing out. That's a pretty simple fix. But if your brushes start to wear excessively quickly it might be because the commutator has become uneven and is eating up the copper brushes.

That is, when it starts to look like this:


and when you remove the endcap you're faced with something like this:


The solution?  Mount the whole assembly in a drill like so:


and take to it with a single-cut file.  It's a makeshift lathe!  After a few minutes:


Make sure that your copper has plenty of thickness remaining; you shouldn't try this if there's not much left of the pads.  After you smooth them out with the file, use some garnet paper and then emery paper to clean up the surfaces.  Then clear out the spaces between the individual copper pieces so that there's no connections between neighbouring pads.  You'll probably have a small ridge at the armature end of the copper, so don't forget to clear between them here as well.  I used a dental pick to scrape between each pad.

I've done this with a couple of starters, with great results.  It's possible to replace the copper entirely, but you need an actual lathe to do that.

[sandebud]

Hey there. My 700S wasn't starting for some reason, so I eliminated problems with the battery, solenoid, and charging system, which lead me to the starting motor. I removed and disassembled the motor, and it stunk to high heaven! Well I cleaned it all up, put in new grease, and viola! the thing started right up. But... only once. Now it won't start again. I wonder if I should try your suggestion here and clean up the commutator. BTW, I wonder if you have a picture of the endcap reassembled. What are you supposed to do with those copper wires?
Thanks
John

[draser]

In your case it may be that the brushes get stuck in the holders, hence no start. I'd check length, they may need replaced, and make sure they move freely in holders.

This was pretty common on cars and a quick tell was tapping the motor with a hammer handle, which released the brushes, that worked for a while.

[mollusc]

The "copper wires" parts are the much more common rebuild -- as said, those lead to the copper brushes.  The undulating commutator only seems to arise after a long time.
If you don't see any small black blocks on the ends of the braided copper wires, it's time to replace the brushes.  I've also had brand new brushes fracture after a couple of weeks, necessitating another rebuild pretty quickly.

[sandebud]

I found 2 other copper wires attached to the end cap that did not have brushes attached to them, in addition to the two that did. What am I supposed to do with those? Are they supposed to have brushed on the end of them, too? I'll post a picture after work today.

[sandebud]

OK... I think I know the problem now. After making that last post, I googled the brush holder set for this bike and found out that there are supposed to be brushes at the end of those copper wires that attach to the holder. Mine does not have them, so no wonder I'm having issues. I'm going to order one along with a new terminal set and see what happens. Stay tuned.

Thanks for all your help!
John

[draser]

So.. 2 out of the 4 brushes were gone... hmmm.. I'm an EE by training and have never seen that yet... live and learn. Can you post a pic of the brush holder plate?

[sandebud]

Sorry for the delay in responding. Yes, the 2 brushes that should have been attached to the copper wires are completely gone. The other two are simply worn down a lot. (I'd post a picture, but I've run out of patience in figuring out how to do so.) I just decided to go ahead and order new brushes and end cap, which cost me all of $50. While I wait, I wonder if you guys could advise me on whether to put grease on the attenuator when I put it back together. There was a ton of it on the inside of the canister when I took it apart, which leads me to believe it's designed to operate that way. But most starters require clean attenuators, right?

Thanks in advance.

[mollusc]

Re: pictures.  Follow the directions in the help post about how to do it.  They're very clear.