Starter motor repair

[moto]

My battery holds a full charge, when using the starter button the volts drop to about 7 and back upto full again when the button is released.

Someone said this could be a problem with the Commutator, never heard of it before.

So I checked and cleaned all cables between battery and starter.
The starter securing bolts were tight.

I took the starter motor off, there is lots of fine black dust everywhere inside.
I plan to clean it everywhere with acetone, is it safe to sand inside the yoke with number 600 grit sandpaper? Maybe it's not necessary to do this and acetone will be sufficient.

Following instructions in the manual regarding inspection and repair.
I need to buy some 600 grit sandpaper to clean the commutator.
I measured the commutator at 28.5mm, the wear limit is 27mm so it has some life left.

The mica is supposed to have an undercut to ensure proper operation of the commutator, it has not, it is flush.
So I need to undercut the mica to 0.7mm, it seems quite a hard material, what is the best way to trim/shave the mica off?

Just those 2 questions for now.
It is an 2003 XT600E with about 8000 miles on the clock.

[fiery tupp]

Someone said this could be a problem with the Commutator, never heard of it before.


More likely a problem with the cold
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If you can't fix it with a hammer , use your head .

[baldy]

Sounds like a weak battery to me.
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One day i will rule the world, just not today.

[Noxious89123]

Acetone isn't really the best cleaning fluid you could use. It'll melt paint and some plastics.
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'06 Honda CBR125RW-6 ~ '00 Honda CBR600F-Y ~ '07 Honda CBR600RR-7 ~ Bikeless
'53 Ford Ka 1.3 ~ '03 Vauxhall Astra SRi 1.8 ~ '52 Vauxhall Astra SRi 2.2 ~ '53 Vauxhall Astra GSi

[moto]

baldy, that's what someone else suggested so I bought a brand new one and followed theinstruction regarding filling and initial charge, it did not help.

Then I bought a multimeter and found out both batteries are fine and holding a full charge so I could have saved myself the money.

Noxious, what would you suggest using instead of Acetone?
What about using the grit paper inside the Yoke, bad idea?

Anyway it needs a good clean and the Mica needs trimming.

[andym]

Silly question, is the starter still working?

If not, can't you just attach a couple of wires to one of the batteries and touch it against the correct parts of the starter and see if it goes?

I rigged up an old brake light and connected it to the starter to see if power was actually getting to it.

[moto]

It's not a silly question andy, I should have explained it better.

Originally through lack of knowledge I thought the battery was rubbish because it would turn the starter motor over but not fast enough to start it.

I did not know what a multimeter was let alone own one but when I bought the new battery and fitted it the same thing happened.
Then I bought a multimeter and tested the old and new batteries and both are good, fully charged and they hold their charge.
With the multimeter connected to the battery I tried the starter button and the volts dropped to 7 ish when cranking but go back up when the button is released.

I checked and cleaned all cables between battery and starter.
The starter securing bolts were tight.

I was told "Dodgy brushes in the starter motor or dirty commutator can cause these symptoms."
So I managed to get hold of a workshop manual where it explains the procedures for the starter motor if it does not operate.

Checking continuity on the fuse (it's fine)

Check the battery condition (I know this is good)

connect starter motor cable and battery positive terminal using jumper lead

Disconnect starter relay coupler, connect battery and frame to starter relay coupler with jumper leads

Test main, engine, sidestand, neutral, start and clutch switch

There is also an exploded diagram of the starter, instructions on how to dismantle and reapir.

I would buy a new starter motor but would hate to find out that is not the problem like I did with the battery because it costs £334 + VAT.

So I am going to clean up the brushes with wet and dry and clean the rest of it and get rid of all the dust and re-assemble.

[andym]

I wouldn't have thought a build up of dust would cause it to stop working.

I should point out I'm full of these silly questions.... so here goes... have you actually checked to see if you can turn the starter motor? My old one was seized solid, and a couple of taps with the handle of a hammer apparently destroyed the inside (4 magnets were in about 20 bits and lots of small fragments).

I would try the simple stuff first save a lot of time and money.

Although in saying that.... I thought my scooter had a single filament rear bulb that just lit brighter when I pressed the brakes.... so I spent the best part of 3 hours stripping everything down, checking all the connections and wires, various other things then eventually checked the bulb itself... imagine how cheesed off I was when I found it was a double filament bulb and one had blown

[Vincent]

You're right about the commutator, the copper part wears and you need to cut back the insulation inbetween. Last time I did this with a folded piece of wet and dry but you can also use a micro file. I would start by replacing the brushes though, see how that works. Make sure the bushes for the commutator shaft, (in the housing and the cap), are ok and check to see if the starter motor has been apart before - sometimes shims are left out on re-assembly. There are several places that specialize in refurbing windings on starter motors and alternators etc, mainly for cars but some can do bikes too. Elektrexworld are very good but hardly cheap, 'usualy better to try and find a decent used motor.

[alains]

on my file for the NSR125 i have a detailed tuttorial with home made tool , here is the part for
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the worst day fishing is better than the best day working

[moto]

Thanks for the replies.

It does not look like the starter motor has been apart before, all the shims etc are there according to the manual.

The starter motor does turn free by hand.
When it was connected to to the battery it turned the engine over slowly, it sounded like it was struggling.

How can I differentite between a fault with the starter relay and the brushes?

The brushes are £70 from fowlers, so I don't want to buy them unnecessarily.

[Vincent]

[moto]

There are 2 brushes seated on the end plate which look good as do the springs.
But there are 2 brushes seated in the stator or yoke (whatevver you call it) and the bit of metal holding them together is broken.

I did not notice this before as I did not know they were originally connected.

Could this break cause the problem? I'll post some pics.

[moto]

Sorry for the double post, my PC is so damn slow.

No I have not tried anywhere else for brushes, don't know of anywhere else.

If the problem is caused by that break in the picture then it looks like I need to buy the whole brush plate, wish I could just but the bit that is broken.
Are the pics showing in the post above, I'm just seeing a red cross.

[alains]

the brushes look good enough , you should clean the comutator as shown above , then oil or grease the bearings . with a fully charged battery it should turn as new
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the worst day fishing is better than the best day working

[moto]

Yeah the brushes look ok but would the broken metal piece holding the 2 on the yoke together cause the problem?

[herulach]

POssibly if it's allowing the brush to move. It looks like it might be possible to fabricate something to replace it, or source it from a dud one at a breakers.
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YBR 125>FZS600

[alains]

could it be a question of insulation ?
i dont know this starter , but the brushes must be insulated fromn the body , warm your multimeter
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the worst day fishing is better than the best day working

[moto]

[Vincent]

[Vincent]

It might be worth getting in touch with Electrex World and asking if they do a replacement brush set.

They've always been very good when I've rang them.

Alternative might be to get the clip brazed.

[Walloper]

Therew are more parts in a starter than commutaor, mica insulator and brushes that can fail.
The armature has a copper wire winding this is special wire that with a very thin coating of insulation. The commutator connects these wires to the battery via the brushes.
If there is a failure of the insulation this thin copper wire will short circuit.
If it short circuits then the motor will not have enough Oomf to turn the engine.

Starting problems due to other issues, such as low fuel, put more load than normal on the windings which can cause the coating of insulation to break-down/fail.

To test the motor properly the motor's resistance has to be metered.
A Megameter is needed to do this. This puts a heavy current through the motor to ground the meter will show how much resistance the motor gives the applied test current.
Megameters are a more specialised tool most amateurs don't need.

It is a bit of a big bit of something to take a bite of.

You could take the motor to be tested at a bike garage or auto electricians.
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W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair

[Vincent]

On such a low mileage bike, I reckon once you replace the broken clip, you're sorted. Brushes look hardly worn to me and they're usualy the first to go.

[moto]

I managed to get a new clip for £18 including postage, assembled it and put the bike back topgether and it started straight away.

I am so pleased to have it running again and surprised a pleb like me could do it as I did not even know where the starter motor was or what it looked like before this problem.

Thanks a lot for all the help vincent, walloper, alains, herulach, andym and noxious.

[Vincent]

Cool. For future reference, where did you get the clip? Was that with the brushes?