Testing a starter motor

Brian Laws

New Member
I pulled the starter last night and it does look like its in pretty bad shape. It was missing one of the long bolts that hold the three outside pieces together.

I need your help to make sure I am testig the armature assembly correctly. Wear is OK, so next up is the resistance. The manual says the communtator (smaller end of the armature) should have between .009 & .011 ohm. I used my tester on the 200 ohm setting and it is bouncing between .2 to.3. Did I test this correctly?

It also says to test the insulation resistance. It is supposed to be above 1 M OHM. I set my meter to 2M OHM and did not get any readings. Also tried 200K and 2K, but still nothing. if I am testing this correctly, then I guess I found the problem. Any electricians out there that can validate my findings?

Thanks, Brian
 

bigkaley

Control Rider
Brian,
Well, glad to hear that it was isolated to just the starter! If one of the long bolts that holds the body of the starter together was missing, there's a good chance that it may have been a "mechanincal" problem in that the body of the starter may have mis-aligned almost jamming the starter. As far as the electrical tests, I'm getting better with them, but I'm still a little "new" and depending what tester you're using there is usually a way to "zero" the the tester when checking at least Ohms and maybe some other tests. I don't have my tester here in front of me, so I going off of memory :dunno: There should also be a bench test to activate the starter using the battery and the positive and negative lead. Keep me posted and best of luck!
 

Brian Laws

New Member
Yea, I am just using a digital multimeter. I tossed the instructions long ago, but I will try to look up the directions for zeroing the device. As for bench test, its odd the service manual does not describe that as a testing option. I have read in two different do-it-yourself forums about how that is a standard starter motor test. I may give it a try after work.
 

Brian Laws

New Member
You were right about the bench test. Just connect power and ground the unit to the battery...should turn the starter if working properly. Terrance brought one by and it turned so my old one is definitely bad. I should have a new one in a few days.
 

Quantum_Ape

New Member
I think i might be able to help.

The instructions for testing the multimeter according to your post says the correct resistance should be between .009 and .011 ohms. If your testing the multimeter using a 200 ohm range, then it wont have the resolution you need to get an accurate reading. Your going to need a setting closer to 1 ohm or below. If your using an analog meeter you probably don't have a setting this low. Your best bet is to get a digital multimeter, even a cheep one should work. Note, a cheaper meeter will have a larger percentage of error. The manual will tell you how much the meter might be off and thats ok. The big thing you want to look for is if you get no reading from one of the pair, which would indicate that there is a brake in the winding.

As for the insulation, you wont be able to test this without a very expensive meeter specifically designed for insulation. 1 to 2 M ohm stands for mega ohm. To give you perspective, your wire you are measuring is in the milli ohms. Lets use 1 ohm as a base.

a milli ohm is .001 ohm
a Mega ohm is 1,000,000 ohms

your setting your meeter to kilo ohms which is only at 1000 ohms.

So you can see how the insulation is way higher than a standard meeter can test. There are other things to consider for the insulation, but i wont go to far into it.



So to summarize, and hope that i haven't made things too complicated, this is what i would do.

Using a digital multimeter, test the windings. If all checks out, you can assume the insulation is ok. If its not ok, generally you can see burnt marks all over the wire and the resistance will be very low, close to .001 or below.

If that checks out and the starter spins freely when you turn it. Then hook it up to a 12 volt battery and see if it turns. If you don't have a charged spare laying around. Take the one in your bike out completely and use jumper cables. Make sure the negative terminal denoted by a minus sine is attached to either the black lead on the starter, or the case of the starter as many only have one wire coming away from it and use the case for the other terminal. Then use the positive terminal and connect it to the red wire or where ever you would attach a wire to the starter. Beware starters have lots of torque and can jump when it starts. You might want to put it in a vice first.

If it turns your good to go, If it tries to turn or jumps around then there are either windings that are actually bad, or you are having issues with the carbon brushes that provide power to the windings. Those are the most common issues in this case.

If any of this is too confusing or i did a bad job explaining please feel free to let me know. I will be happy to help out any way i can. If your interested in knowing more about electronics or testing them, just let me know and i can help there too.
 

Brian Laws

New Member
Sounds like you really understand this stuff, so let me ask another question. From what you described I cannot test for resistance over 1M Ohm. Which setting should I be using to check for a resistance between .009 & .011?

My digital multimeter has several different settings for testing resistance and I am not sure which one I should be using. (200, 2K, 200K, 2M) (also has a solid right arrow with a vertical line going through it). Of course I tossed the manual as I have only ever used the multimeter to test voltage.

Even though I am sure the starter is bad, I wouldn't mind knowing what is bad and possibly fixing the starter as a spare or to recover some of the cost of buying a new one.
 

Quantum_Ape

New Member
No problem, I'll be happy to help out. The arrow with a line going through it should be to test diodes. It's a type of electronic component that only lets electricity flow one way through it. For testing a starter you won't need this setting.

As for the available settings on your multimeter, if your choices for checking resistance are 200, 2K, 200K, 2M, your best bet is the 200 ohm setting. As for the range, while you have a 2M ohm setting, you cant test insulation with this. I don't know if your using a digital (shows numbers) or analog (has a needle that moves back and forth). If it's analog and the lowest setting is 200 ohms then you definitely can't measure this with this multimeter. If its digital the answer is more complicated. Chances are though that if your lowest setting is 200 and your only getting readings with one decimal place over into the tens, it's not going to be sensitive enough to accurately measure the resistance.

Not to worry though, there are a couple of tricks you can use here. To keep it simple, with the multimeter on the 200 ohm setting, look at what it says with holding the probes in the air. Then look at what it says when you touch them together. Use these two reading to indicate either a brake, or a good wire. Try testing each of the windings like this and if none of them have the reading that you get when you just hold the probes in the air, then there is a 70% chance the windings are fine.

Now keep this in mind. It's almost impossible for all your windings to go out at the same time because as soon as one fails, it stops turning reliably. Hence the other windings stop getting used.

I understand you did a bench test already. When you put power to the starter, does it turn at all or show any sign of life? Another thing to try is hook up the power and if it's not turning take something you can move the rotter on the starter with to see if it suddenly kicks in and spins. BEWARE starters are powerful motors. Don't use anything that will get caught on the rotter or somehow yank on you because it can cause some damage or really hurt you. Just use your head and be careful if you try turning the rotter as it could suddenly kick on.

Where i am going with this is if nothing happens then more than likely there is an issue between the contacts on the outside of the starter and the carbon brushes inside it. Another way to test this is to hook up that multimeter on your lowest (200) setting and put it on the contacts for the starter. Make sure you do this with no power to the starter. You should get a reading. What it says isn't as important as the fact you get one at this moment. Now very slowly turn the rotor by hand. You should have a changing resistance as it jumps from contacting various coils inside the starter. What your looking for are dead spots, or no reading at all at any position.

If you are getting dead spots by doing this check, then you have a bad connection between the carbon brushes and the coils inside. If you get no readings at all, then there is more than likely a break in wire inside connecting the brushes to the leads outside.

I would start here and see what you come up with. The results you get in these test will decide what you look at there after. Also if you need more one on one communication, you can PM me and i will give you my number if talking would be easier for you. Otherwise i will be checking back here and doing what i can to help.
 

Brian Laws

New Member
I appreciate the detailed how-to. I tested the commutator on the 200 setting and it is bouncing from .2 to .3. Mine is digital BTW. As you stated, it only goes to one decimal place, so I can't tell the true reading. Perhaps I need to go buy a better multi meter. I noticed Walmart now sells a self adjusting meter so you do not have to select the setting. It is simply Ohms, AC, DC, etc.

I will try some more bench test options as you stated above as well. Should be interesting to see if it has a dead spot like you mentioned.
 

Quantum_Ape

New Member
An auto ranging meter is definitely a good thing. Saves lots of headache and lower the chances of damaging the meter. You might want to check out radio shack. They will have a better selection with better quality. And if your lucky the people in there might know what they are talking about and can show you a couple of good options. Just check the specks on the package for Ohms and you should be all right.
 
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