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1Back to top Go down    87 K100 Light Oscilation Problem on Thu May 05, 2016 6:52 pm

JLS

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Hey all,

This is the second season with my bike and I have found an intermittent problem that has seemed to gotten worse. My bike is mostly to work and back daytime riding, but last night was my first out of town jaunt. My son and I were playing leap frog through town, so he saw me at all angles as it was getting dark. When I pulled in behind him at home right at dusk, my headlight was off and my instrument panel backlight was off. My son also reported on the highway that my tail light was going on and off. I noticed reflective signs were also bouncing light back in the same oscillating fashion riding normal speeds through town.

I shut down with the kill switch, but when I flipped back to on (not start), everything came to full brightness. I hit the starter and it took a little too long (in my opinion) for the lights to come back. Just siting in place for a few minutes running, no issues. Engine revving caused the standard light brightness increase, and back off slightly when back to idle. Sitting in place and trying to shake the crap out of the running or off (but lights on) bike does nothing to repeat the issue. Starts strong every time! The phenomenon only starts to happen during riding.

Any way, long winded story. Where do I start to look on this? I consider it a safety issue and will not ride it that way.

Jake

    

2Back to top Go down    Re: 87 K100 Light Oscilation Problem on Thu May 05, 2016 7:29 pm

Inge K.

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Search the forum for "dirty starter commutator & LSR"...heaps of threads about this.


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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

3Back to top Go down    Re: 87 K100 Light Oscilation Problem on Fri May 06, 2016 9:51 am

JLS

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I saw a couple posts related to that, it seems a little voodoo to me, but I will try looking at it. Just don't try to tell me my blinker fluid is low! Razz

    

4Back to top Go down    Re: 87 K100 Light Oscilation Problem on Fri May 06, 2016 10:35 am

Inge K.

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@JLS wrote: it seems a little voodoo to me,

Maybe this thread makes it a bit less voodoo. scratch ...saves me some writing.
And yes, correct level of new blinker fluid is a important part of it.


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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

5Back to top Go down    Re: 87 K100 Light Oscilation Problem on Fri May 06, 2016 11:06 am

JLS

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Since I am 50% German, I can say "Those pesky German Engineers!!", using the starter as a ground path....HA!. Schematically it make sense now. Well, gotta pull the tank anyway to replace the blower fan motor, so I will get a 2-fer looking at the relays. Wish I hadn't JUST filled the tank.

    

6Back to top Go down    Re: 87 K100 Light Oscilation Problem on Fri May 06, 2016 7:40 pm

Inge K.

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@JLS wrote:Well, gotta pull the tank anyway to replace the blower fan motor, so I will get a 2-fer looking at the relays. Wish I hadn't JUST filled the tank.

You don't need to remove the tank to get the starter out and clean the commutator and/or renewing the brushes.


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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

7Back to top Go down    Re: 87 K100 Light Oscilation Problem on Sat May 07, 2016 10:55 pm

JLS

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Ok, I did the starter thing today. Had to pry a little to get it out, but it gave up. Checked resistance before opening and showed about .5 or 0,5 as my German friends would write. If I spun it some it would jump around a bit. Once open, I dumped out quite a bit of carbon. I cleaned the comutator? contacts with steel wool and then some 2000 grit sand paper. Sprayed the brushes down with contact cleaner. Once back together, checked resistance. 0,2 ohms and max of 0,5 ohms at any point spinning. Put it back in the bike and took it for quick spin. Actually started stronger. Did not see any light oscillation, but I could not ride too long around since it started to rain. We will see. Oh, I think I need new brushes, one is at the limit of travel in the groove. I think the immediate problem is likely solved. Thanks!

    

8Back to top Go down    Re: 87 K100 Light Oscilation Problem on Sun May 08, 2016 3:24 am

Inge K.

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@JLS wrote:I cleaned the comutator? contacts with steel wool and then some 2000 grit sand paper.
Good that you got it sorted...then new brushes, and the problem will be away for many years.
But don't use abrasive paper on the commutator (good that you did use 2000 grit,probably it doesn't be to bad, tho) as your new brushes will wear out faster, use an eraser instead.


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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

9Back to top Go down    Re: 87 K100 Light Oscilation Problem on Sun May 08, 2016 6:49 am

robmack

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Good advice Inge. The best eraser to use is the one that is made for both pen and pencil - 1/2 for erasing ink, the other 1/2 for erasing pencil marks. The pen side of the eraser is perfect for cleaning all electrical contacts.


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Robert
1987 K75 @k75retro.blogspot.ca
2011 Moto Guzzi V7 Racer
http://k75retro.blogspot.ca/
    

10Back to top Go down    Re: 87 K100 Light Oscilation Problem on Sun May 08, 2016 10:12 am

JLS

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Thanks, and saying "sand" and "2000, grit doesn't really go hand in hand. It was automotive paint finish paper. The steel wool did almost all the work. I will keep checking back when the inevitable problems arise. Appreciated he help.

    

11Back to top Go down    Re: 87 K100 Light Oscilation Problem on Sun May 08, 2016 11:21 am

Inge K.

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@JLS wrote:Thanks, and saying "sand" and "2000, grit doesn't really go hand in hand.

Hmm...yes, a 2000 grit you can use as a toilet paper without any following problem.


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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

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