Starter Brushes turned to dust

[ChicagoRob]

Hello All.

I had some starter problems today so I pulled the starter and the brushes had turned to dust.

These were new brushes from Stocker's because the old ones had done the exact same thing.

Something is wrong. Any dieas what it might be?

Thanks,

Rob

 

[Nessism]

Is the commutator smooth or is it tore up and rough? Maybe the brushes are wearing down prematurely due to roughness.

 

[Redman]

I would think The brushes didnt all turn to dust at once,
but more like they were ground away by the commutator bars.

Entire brush did not turn to dust and only have a wire remainting. Is still some solid brush remaining, I suspect. Mine were wore right down to almost the wire and so not much spring tension remaining. Sometimes would turn over well, other times not. (Mine the 4 brush Mitsuba. I understand there can be one of 3 or 4 different manufacture/type of starter in any one model/year bike.)

Are other postings about how to dress the commutator bars.

I did it with just a drill motor and some emmory paper on a paint stir stick.

Before. Not really that rough, but not smoothe, either. But was a bit tapered and not flat.

After. Could have been better. But was an improvement over what it was, and fairley good for doing by hand, I thought. (I had seen machinest do this on industrial generators. They had portable lathe like equipment and all sorts of measuring devices.)

Also be carefull to remove any thing that might get stuck inbetween the commutator barrs. Scratch out with a knife edge or something.

.

 

[SqDancerLynn1]

I would get someone to turn it in a lathe & polish it. ALso you might have a problem with the starter clutch being slow to release. I had my starter hang up and not release, it distroyed the starter

 

[Guest]

Check your grounds.

 

[ChicagoRob]

Good one Chef. I lol'd.

As usual, you gentlemen are correct. When I put the new ones in I only gave the commutator bars a cursory cleaning. They were rough. There wasn't just dust, there were some larger pieces as well so it must have been very rough.

Here's the after of my initial attempt at smoothing them out with 320. As you can see, something marked it up pretty good. When I run my finger over it, it doesn't feel round. It feels like the center of each bar is higher than the edges. It feels like a series of small speed bumps. I hope that makes sense.

I think at this point I'm better off taking it to the machinist or springing rebuilt one from Stocker's.

What are the chances of the machinist messing it up? If this one goes bad, then I'm out the core charge too...

Thanks again everybody. This has been a great help.

Rob

 

[tkent02]

Just get a used one from someone on here.
I have one from a 1100L, if you want it PM me.

 

[Clone]

If your brushes wore out so quicky I would suspect that your starter switch is sticking, so your starter runs while the engine is on.

 

[argonsagas]

I would get someone to turn it in a lathe & polish it. ALso you might have a problem with the starter clutch being slow to release. I had my starter hang up and not release, it distroyed the starter

This is a good point. I lost one starter-brush set within 100 miles, when the starter clutch did not release.

The most likely thing is the commutator, which can get very rough and uneven, and both can cause rapid wear on the brushes.

Often this can be cleaned up with sandpaper or, if too far gone, with a file.

Note the risk to the insulation on the windings with any such work and NEVER let the sandpaper/file/other tool touch them.

I have done mine with an electric drill locked in a vise, and a smooth, flat, file. A dill press is better than a portable because the chuck has less chance of lateral movement.

 

[ChicagoRob]

Excellent point. I did install a new stator, so perhaps I jostled something and now it's not disengaging properly.

How can I tell?

Thanks for all the help,

Rob

 

[Redman]

..........
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Here's the after of my initial attempt at smoothing them out with 320. As you can see, something marked it up pretty good. When I run my finger over it, it doesn't feel round. It feels like the center of each bar is higher than the edges. It feels like a series of small speed bumps. I hope that makes sense.
..........
..........

Rob,

Very good description of each bar, I think that can happen if hold the emeory paper with your fingers. Works better if hold the emeory paper with something hard and flat like a piece of wood (I used paint stir stick). Problem with that hump is not so much that it would mechanically wear the brushes, but that will have less surface area contact between bars and brushes, and all that current distribted over this smaller area, so more current per surface area and more heat. And might actaully limit how much current can flow. Needs to be flat (well, not exaclly flat, but cyclinderical) for more surface contact between brushes and commutator bars.

I suspect that wear spot in center of edge of each bar (I see in photo, not what you mentioned unless that what you mean by something marking it up) is from when the brushes were worn down to that connector for the wire, and that connector and/or the wire ground into the bars. WOuld have to take off a lot of material to get down past that, so maybe not worth the effort. BUt do work on it some more to take out the "speed bumps".

About the starter clucth not relaesing, I have not had that happen, but I understand that even at idle or just above idle that can hear the starter motor whinning and growling. And engine not rev up as quick as it should. Note: This is if the starter clutch doesnt realease. (which is different than if the starter motor is still running).

.

 

[ChicagoRob]

Thanks Redman.

The machinist that I've been using wouldn't touch it, so I'm on my own.

I did as you advised and worked on it a bit more. I clamped the motor end of the casing in a vice and chucked the armature in a drill. I had a file that was just the right width, so I cut some inch and a half strips of sandpaper and wrapped them around the file. I started at one end of the strip and slowly worked my way back until the paper was fouled. Folded the paper over and did it again. I worked my way from 220 up to 1000. Attached is the result. The sandpaper in the photo is what the 1000 looked like after I was done.

I got the marks out and now it's smooth. The rebuild kit from Stocker's comes tomorrow so I should be starting it tomorrow night. I know that the starter button isn't sticking, so I'll listen for the starter still turning when it's idling. I think that I'd be able to tell. I guess that I could always put the volt meter on it because if the engine is turning it, it should be generating some electricity. I'll pull it again after I've started the bike a few times to make sure that it's not tearing up the brushes again.

Thanks for the help everyone,

Rob

 

[Guest]

Looks good Rob, nice work

 

[pntrdave]

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