Author Topic: Lost all power to bike while riding  (Read 882 times)

Offline andrew.powell

  • Curious
  • Posts: 4
Lost all power to bike while riding
« on: May 10, 2022, 07:33:47 PM »
Hi All, new K100 owner here and excited to join the community (and get my bike running). Also very novice in terms of mechanical experience, so may require some patience. I inherited an 85 K100 LT a few weeks ago, and finally got it going this weekend after replacing the load shed relay and fuel pump.

The first thing I did on my first ride was drop the bike on some wet leaves leaving my driveway. Ugh. It was very minor and didn't cause any damage, just got the bike a bit muddy. After picking it up, I rode it around for a few (maybe 3-4) miles and while heading home, I stopped to make a turn, but realized the bike had lost all power, no dash lights, nothing (very similar to the bike pre-new load shed relay). Interestingly, if I turned on the kill switch, the headlight and horn would work, but nothing else. I first tried to mess with the load shed relay some more, and now the headlight comes on if I turn on the ignition regardless of the position of the kill switch, but nothing else works, including the horn.

I checked the battery with a multimeter, and it is fully charged. Any ideas on what could have happened over such a short ride? Could dropping the bike have knocked something loose? Based on my initial search through this forum, I figured I would try to clean out the ignition switch and give the starter a few whacks with a wrench.

Anyways, looking forward to hearing what you all have to say. Given the shape of my bike at the moment and my lack of know-how, I may be on here quite a lot!
  • Oregon
  • 85 BMW K100 LT

Offline The Mighty Gryphon

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Re: Lost all power to bike while riding
« Reply #1 on: May 10, 2022, 09:32:43 PM »
Welcome!  I would get the ignition switch cleaned before doing anything else.  Your problem sounds a lot like when the ignition switch on my RT acts up.  It isn't a terribly difficult job, just take your time and be very careful that you don't drop any of the springs. 

http://www.eilenberger.net/K75S/IgnitionSwitch/

The hardest part for me was removing the screw that holds the switch onto the ignition lock.  Get a screwdriver that fits the screw as perfectly as possible to avoid damaging anything.  THe screw is help in place with red Loctite that has a very strong grip and can only be released with heat.  Unfortunately, everything around the screw is plastic so you can't use any heat to loosen it.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline foliver

  • ^ Proficient Motobricker
  • Posts: 194
Re: Lost all power to bike while riding
« Reply #2 on: May 10, 2022, 10:02:06 PM »
Hi, Mighty is right about the little screw.
I didn't knew of his existence, so when unmounting, i've broke it.
I was lucky cause another ignition switch was with the parts the seller gives me along with the bike lot of years ago.
So i cleaned and used the old one.
The screwdriver is a flat tiny one. Get a proper one for that.
  • Montevideo, Uruguay
  • Bmw K75C 86

Offline Laitch

  • Faster than a speeding pullet
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Re: Lost all power to bike while riding
« Reply #3 on: May 10, 2022, 10:40:36 PM »
The kill switch doesn't kill the headlight.

Be sure the battery terminal cable connections are tight and that the battery negative cable attached to the transmission on the shifter side of the moto is bolted tightly. Check the plug for the Jetronic control under the seat and verify that you cannot disconnect it by pulling the right side of the plug (where its cable is attached) outward.

There's a K100 rider's handbook in the Service Manual section of this site that you can download to familiarize yourself with your moto's equipment, if you don't already have one.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles
I wept because I had no radials until I met a man who had no splines.
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Offline frankenduck

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Re: Lost all power to bike while riding
« Reply #4 on: May 11, 2022, 12:52:40 AM »
Why did you replace the load shed relay and what did you replace it with?

(It's usually the last thing that you messed with that causes a problem.)
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Offline andrew.powell

  • Curious
  • Posts: 4
Re: Lost all power to bike while riding
« Reply #5 on: May 11, 2022, 11:44:48 AM »
Thanks so much! The bike is currently marooned a few miles away for obvious reasons. However, I'll try each of these later this week when I can get to the bike and report back.

I ended up replacing the load shed relay after borrowing a set of tester relays suggested that the relay was bad. I ordered a replacement Hella relay off of Amazon (https://www.amazon.com/gp/product/B004NIKVWC/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1) as the relay had a pin configuration that isn't easy to find these days. I also realized that I had a few extra replacement relays in the trunk of my 84 633 csi with the correct pin configuration. That actually worked really well for a few miles before the bike went dead. I tried replacing the relay with the other spares with no luck.
  • Oregon
  • 85 BMW K100 LT

Offline andrew.powell

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  • Posts: 4
Re: Lost all power to bike while riding
« Reply #6 on: May 15, 2022, 03:08:24 PM »
Update - I finally got a reprieve from the rain yesterday and was able to work on the bike. Turns out it was the ignition along. I cleaned it out and secured some of the wiring and it's running great.

Thanks for all the help. Glad it was something relatively simple.
  • Oregon
  • 85 BMW K100 LT

Offline The Mighty Gryphon

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Re: Lost all power to bike while riding
« Reply #7 on: May 15, 2022, 06:59:51 PM »
Do you mean the ignition switch or the coils/ICU?
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline andrew.powell

  • Curious
  • Posts: 4
Re: Lost all power to bike while riding
« Reply #8 on: May 18, 2022, 12:06:18 PM »
It was the ignition switch. The switch itself had a lot of gunk in it, and the wires leading into it were jerry rigged. After cleaning all that up the bike started right up.
  • Oregon
  • 85 BMW K100 LT

Offline The Mighty Gryphon

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  • Posts: 6617
Re: Lost all power to bike while riding
« Reply #9 on: May 18, 2022, 03:35:14 PM »
 Nice job!  112350
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

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