Author Topic: The 85 K100 - Starter Wiring Projeckt  (Read 1713 times)

Offline jmccrary

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The 85 K100 - Starter Wiring Projeckt
« on: October 04, 2018, 11:53:07 PM »
Hello everyone!  I posted a similar question on the K100 forum, but hoping someone here can help also.

On the starter relay, there is a post that hooks directly to the positive post of the batter and the other post on the relay goes to the only post on the starter motor.

When checking with a voltmeter, the post on the starter motor and on the relay that it connects to are showing to me as a ground.  When I press the starter button, well it stays as a ground.  I attempted to jump it manually with a positive cable (after removing the starter lead from the relay, and just a spark...so I immediately stopped.

Can someone please explain this to me?  Looking st the wiring diagram, it appears to be right...but shouldn’t that either be positive, at lease when the starter button is pressed? And, when bypassing the relay, why is it still ground?

Unless the starter is broken, I am baffled.

Thanks for the help!!!

1985 K100 RT

Justin
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Offline Laitch

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #1 on: October 05, 2018, 01:23:08 AM »
On the starter relay, there is a post that hooks directly to the positive post of the batter and the other post on the relay goes to the only post on the starter motor. . .  . I attempted to jump it manually with a positive cable (after removing the starter lead from the relay . .  .  Looking st the wiring diagram, it appears to be right...but shouldn’t that either be positive, at lease when the starter button is pressed?
Using the attached diagram, I'd like you to indicate which wire you jumped, which you disconnected, which was your source of current and which was the one you thought should be positive when the starter button was pressed. Did you disconnect the black wire running from relay to the starter and then run current directly to the starter from the battery? What was the purpose of this trial?


  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline jmccrary

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #2 on: October 05, 2018, 07:11:28 AM »
Laitch,
Looking at the diagram you posted, I removed the black wire.  Ok, I know, there are two depicted on the diagram.  So, lets number them and then I will describe what I did.

On the Starter Relay there are four posts, lets label from the left to right; 1, 2, 3,4.

On the Starter Motor it depicts two "wires", but from left to right, we will have wire 5 and wire 6.

Now, we know that wire 6 does not technically exist as this is the ground from the starter motor body.

So, this is what I get when testing with a voltmeter and how I jumped the wires.

Key off:
Wire 1:  12v positive
Wire 2:  12v positive
Wire 3:  12v positive
Wire 4:  12v negative
Wire 5:  12v negative

Starter button pressed:
Wire 1:  12v positive
Wire 2:  0v
Wire 3:  0v
Wire 4:  12v negative
Wire 5:  12v negative

I removed wire 4 from the post and tested the voltage on the wire, it was 12v negative.
I tested the voltage on the Starter Relay post where wire 4 is after removing the wire from the relay and it was 0v.  Pressed the starter button, 0v.

Using wire 5, I jumped this across to wire 1 to try to spin the starter motor.  This just caused a lot of sparks.

Voltage test of wire 5 when I disconnect the wire 4 from the relay post:  12v negative

I think the starter is shorted out and time for a replacement.  The purpose of this, is because all bike was fully disassembled, rewired with a m.unit blue, and now that everything is coming back together, so I am individually checking each component to make sure it still works.  The Starter was removed and did end up having a fall from the bench.

Thanks again!!

Justin
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Offline jmccrary

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #3 on: October 05, 2018, 07:19:04 AM »
Oh, one last thing, with the starter motor disconnected from the relay, so wire 4 removed, pressing the starter button I did not hear any audible "clicks" coming from the starter relay.
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Offline johnny

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #4 on: October 05, 2018, 07:28:33 AM »
greetings...

motogadget munit blue... what other bastardization have you not told us about...

j o
  • :usa#1 i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin :usa#1

Offline jmccrary

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #5 on: October 05, 2018, 07:47:21 AM »
Ummm...I think that is it...
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Offline johnny

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #6 on: October 05, 2018, 08:41:35 AM »
greetings...

does this moto have unbastardized oe instrument cluster...

post up some photos of this moto...

j o
  • :usa#1 i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin :usa#1

Offline jmccrary

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #7 on: October 05, 2018, 08:44:36 AM »
greetings...

does this moto have unbastardized oe instrument cluster...

post up some photos of this moto...

j o

Of course that was replaced...but...I can put the oe cluster on if needed. Photos...will try to get some tonight.
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Offline Laitch

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #8 on: October 05, 2018, 08:49:10 AM »
So, this is what I get when testing with a voltmeter and how I jumped the wires. . . .
The Starter was removed and did end up having a fall from the bench.
Breathtaking!
Did you put 12V to the starter on the bench before it hit the floor or after it hit the floor?
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline johnny

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #9 on: October 05, 2018, 08:52:25 AM »
greetings...

before i tell you what you are doing wrong i would like to know what bastardization has been done to this moto...

you didnt tell us about the munit in your 1st post... and when a asked about other baztardization you indicated noting else...

now you are saying there is additional bastardization such as the instrument cluster...

so... gimme the list... what has been bastardized...

j o
  • :usa#1 i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin :usa#1

Offline jmccrary

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #10 on: October 05, 2018, 09:00:09 AM »
Breathtaking!
Did you put 12V to the starter on the bench before it hit the floor or after it hit the floor?

Only after.  Should the post on the starter be showing as negative?
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Offline jmccrary

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #11 on: October 05, 2018, 09:03:41 AM »
greetings...

before i tell you what you are doing wrong i would like to know what bastardization has been done to this moto...

you didnt tell us about the munit in your 1st post... and when a asked about other baztardization you indicated noting else...

now you are saying there is additional bastardization such as the instrument cluster...

so... gimme the list... what has been bastardized...

j o

The motor is original...but honestly, the full wiring has been redone, only using the fuel and starter relays.  Oh, the original computers are being used...but everything else, replaced.   As for asking about "bastardized" if you are asking what has been modified, electronically everything really...mechanically, just the frame.
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Offline johnny

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #12 on: October 05, 2018, 09:17:49 AM »
greetings...

did you loop your bike...

j o
  • :usa#1 i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin :usa#1

Offline jmccrary

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #13 on: October 05, 2018, 09:59:16 AM »
greetings...

did you loop your bike...

j o

Not familiar with loop...can you please explain more?
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Offline johnny

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #14 on: October 05, 2018, 10:25:27 AM »
greetings...

post some photos of your moto and i will show you the loop...

j o
  • :usa#1 i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin :usa#1

Offline jmccrary

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #15 on: October 05, 2018, 10:46:31 AM »
greetings...

post some photos of your moto and i will show you the loop...

j o

PM sent
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Offline rbm

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #16 on: October 05, 2018, 01:51:06 PM »
Only after.  Should the post on the starter be showing as negative?
You should not be measuring any voltage on the motorcycle that shows potential lower than ground.  It's not possible to achieve this, unless the battery is wired backwards possibly.  Now, I'm assuming that you are measuring relative to the negative terminal of the battery and you have connected the -ve lead of the voltmeter (Black) to that battery terminal.  Is that assumption correct?
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline jmccrary

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #17 on: October 05, 2018, 02:33:27 PM »
Now, I'm assuming that you are measuring relative to the negative terminal of the battery and you have connected the -ve lead of the voltmeter (Black) to that battery terminal.  Is that assumption correct?

I do not have them multi-meter in front of me, but yes.

Checking across the battery, i get 13.5 or so volts.  Going from the negative post on the battery to the post on the starter I get 0.  BUT from the positive side of the battery to the post on the starter, I get 13.5v.

However, nobody has indicated if this is correct or not.  Given the minimal amount of knowledge I have about electrical, I think that I should get 0 when checking from the positive battery post to the post on the starter, not 13.5v, indicating the post on the starter is grounded.  I believe the starter has a short in it causing the terminal to be grounded.
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Offline rbm

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #18 on: October 05, 2018, 03:05:02 PM »
Checking across the battery, i get 13.5 or so volts.  Going from the negative post on the battery to the post on the starter I get 0.  BUT from the positive side of the battery to the post on the starter, I get 13.5v.

However, nobody has indicated if this is correct or not.  Given the minimal amount of knowledge I have about electrical, I think that I should get 0 when checking from the positive battery post to the post on the starter, not 13.5v, indicating the post on the starter is grounded.  I believe the starter has a short in it causing the terminal to be grounded.
Yes, what you wrote and what you see makes complete sense.  If you place the Black lead of the voltmeter on the binding post of the starter, and the Red lead of the voltmeter on the +ve terminal of the battery, then you have to read the no-load voltage of the battery. 

The starter motor is a permanent magnet DC motor.  One brush is connected to the binding post and receives battery potential when the starter relay contacts are closed.  Current would flow through the one brush, through the rotor windings and to the other brush. The other brush is wired to ground through the metal body of the motor. The current would continue through ground and back to the -ve terminal of the battery. Since the starter relay contacts are open when the bike is off, the meter is reading the potential of the +ve battery terminal relative to ground (with a very minor voltage drop across the rotor coils and the armature contacts of the rotor).

If you reverse the leads of the voltmeter by placing the Red lead on the starter motor binding post and the Black lead on the +ve terminal of the battery, then the meter will read negative 12V or so, because you are measuring potential relative to the +ve of the battery and not relative to ground with this configuration. 

Isn't electronics wonderful?!
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline jmccrary

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #19 on: October 05, 2018, 03:08:39 PM »
Yes, what you wrote and what you see makes complete sense.  If you place the Black lead of the voltmeter on the binding post of the starter, and the Red lead of the voltmeter on the +ve terminal of the battery, then you have to read the no-load voltage of the battery. 

The starter motor is a permanent magnet DC motor.  One brush is connected to the binding post and receives battery potential when the starter contacts are closed.  The other brush is wired to ground through the metal body of the motor. Since the starter relay contacts are open, the meter is reading the potential of the +ve battery terminal relative to ground (through the armature contacts of the rotor).

Amazing and mind blowing!  Silly question, so hooking a 12v to the post should cause it to turn...assuming nothing is broken lol.

Thanks!!
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Offline rbm

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #20 on: October 05, 2018, 03:15:12 PM »
Amazing and mind blowing!  Silly question, so hooking a 12v to the post should cause it to turn...assuming nothing is broken lol.

Thanks!!
Absolutely correct.  Hooking a battery between the starter motor binding post and the body of the motor will cause the motor to spin.  If you have it installed in the motorcycle at the moment (I mean both the battery and the starter motor, shorting the starter relay contacts by bridging them with a heavy gauge wire will cause the starter motor to spin ... assuming no damage to the motor.  You did mention that you dropped it.
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline jmccrary

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #21 on: October 05, 2018, 03:18:30 PM »
You did mention that you dropped it.

No dropping here, it rolled off the bench lol. I have a 4awg wire at home, I will try to short it when I get home.  In your experience, would it be best just to pull it off and bench test it?
 Thank you for your help!!
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Offline rbm

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #22 on: October 05, 2018, 03:22:03 PM »
That would be my recommendation.  Remove the starter motor from the bike, and clamp it in a vice by the tangs used to secure it to the transmission.  The motor will be in a vertical orientation.  When you clamp the motor, make sure to also clamp a wire; this will serve as the negative lead.  Take another wire from the +ve of the battery and hook it to the binding post.  When you connect the -ve lead to the -ve of the battery, the motor will spin.  Clamping the motor will ensure it is stable, because it produces a lot of torque.
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline jmccrary

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #23 on: October 05, 2018, 03:24:02 PM »
That would be my recommendation.  Remove the starter motor from the bike, and clamp it in a vice by the tangs used to secure it to the transmission.  The motor will be in a vertical orientation.  When you clamp the motor, make sure to also clamp a wire; this will serve as the negative lead.  Take another wire from the +ve of the battery and hook it to the binding post.  When you connect the -ve lead to the -ve of the battery, the motor will spin.  Clamping the motor will ensure it is stable, because it produces a lot of torque.

Awesome, I will let everyone the verdict tonight or tomorrow.  Highly appreciate the help!
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Offline jmccrary

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Re: The 85 K100 - Starter Wiring Projeckt
« Reply #24 on: October 05, 2018, 10:20:14 PM »
And...it works!!!!

Thank you again to everyone!!
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