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Author Topic: new k100rt idles for one minute, then stops  (Read 5021 times)

Offline daveson

  • ^ Quintessential Motobricker
  • Posts: 1268
new k100rt idles for one minute, then stops
« on: January 06, 2019, 01:15:15 AM »
Hi team
I got me a new bike, '84 k100rt, 250,000km. after heaps of attempts i got it going about four times, first time about 2 minutes, the next two times about 1 minute, last time half a minute.
It seams to me a weak spark, even after i replaced the plugs,leads, and coils with known good ones.
Also replaced the petrol tank, pump, filter and injectors with known good ones.
Also tested and cleaned the starter.
My plan now is to replace the temp. relay and check temp. sensor which I'm not sure how to do. I'm planing this cause I'm wondering if the computer is getting a false overheat warning and therefore turning the engine off.
But this is just my random guess, if i knew the proper sequence to follow that would be my new plan.
Thanks heaps for any comments.
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  • Victoria, Australia
  • Current; '85 K100RT~100,000km; four other bricks. Past; Vulcan 1500, V Star 650, KLX 250(dirt bike) TT250(dirt bike)

Offline daveson

  • ^ Quintessential Motobricker
  • Posts: 1268
Re: new k100rt idles for one minute, then stops
« Reply #1 on: January 06, 2019, 02:00:17 AM »
Compression good
Usually runs for about two seconds, so spose starter system good
Sometimes it cranks continuously while starter is pressed, sometimes stops after a second or so.
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  • Victoria, Australia
  • Current; '85 K100RT~100,000km; four other bricks. Past; Vulcan 1500, V Star 650, KLX 250(dirt bike) TT250(dirt bike)

Offline The Mighty Gryphon

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  • Posts: 6843
Re: new k100rt idles for one minute, then stops
« Reply #2 on: January 06, 2019, 09:08:04 AM »
I wonder if you have a problem with the Hall Effect Sensors.   I say this because their signal is needed to operate the fuel pump once the engine is running.  You say the engine sometimes runs for two seconds.  On the Jetronic ECU when the start button is pushed the pump is energized for two seconds, after the two seconds times out it's the Hall Effect Sensors that keep it running.

You might want to look up HES troubleshooting techniques.
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  • 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 natalena

  • ^ SuperNatural Motobricker
  • Posts: 742
Re: new k100rt idles for one minute, then stops
« Reply #3 on: January 06, 2019, 09:53:35 AM »
Silly question, but I got's to know. Is it a new or known fresh charged battery?
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  • MST
  • 1987 K75s #0919, '05 Sportster 1200C, '21 ARGO 8x8, '24 KLR650
"Hard to beat a 10x beaver, 'specially if you're gonna work it."

Offline Chaos

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  • Posts: 3157
  • Mars needs women!
Re: new k100rt idles for one minute, then stops
« Reply #4 on: January 06, 2019, 10:31:29 AM »
I don't think there is an overheat feature that shuts down the engine, just the light. Start simple, clean all the ground cables you can find. 
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  • sw ohio
1987 K75S    VIN 0231
Original owner, Original litter
200,000 miles (plus or minus) and 5 paint jobs
sold 6/23
2023 Ural 2WD sidecar (BMW's bastard step child)

Offline johnny

  • TrailBrakingThrottleWhacker
  • ^ Quintessential Motobricker
  • Posts: 7652
  • Whacking...n...Chopping Sliding...n...High Siding
Re: new k100rt idles for one minute, then stops
« Reply #5 on: January 06, 2019, 10:32:46 AM »
fourepinn
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  • :johnny i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin  :johnny

Offline The Mighty Gryphon

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  • Posts: 6843
Re: new k100rt idles for one minute, then stops
« Reply #6 on: January 06, 2019, 10:58:34 AM »
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  • 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 daveson

  • ^ Quintessential Motobricker
  • Posts: 1268
Re: new k100rt idles for one minute, then stops
« Reply #7 on: January 06, 2019, 03:52:27 PM »
Battery question,  all questions good because there is no mistake that I can't make. Battery good but not new and I've recharged after each of the occasions I've tried.
I'm using a '92 model tank so I bypassed the four pin with scotch locks
I hate to admit it but haven't cleaned the earth's yet,  so that's first on the agenda.
Hall sensors,  that's scary, but I'll read up,  grit my teeth,  and attempt it.
Am I right in calling this an early model rt,
  as stated in workshop wiring diagrams,  since it doesn't have k75 type seat and foot peg plates?
I know about the earth's under the tank but the diagram also shows another multi earth point but where is it on the bike? 
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  • Victoria, Australia
  • Current; '85 K100RT~100,000km; four other bricks. Past; Vulcan 1500, V Star 650, KLX 250(dirt bike) TT250(dirt bike)

Offline The Mighty Gryphon

  • Administrator
  • ^ Quintessential Motobricker
  • Posts: 6843
Re: new k100rt idles for one minute, then stops
« Reply #8 on: January 06, 2019, 10:57:15 PM »
Ground point on engine is above the shifter on the left side of the intermediate section between the engine and the transmission.  It's where the battery ground cable connects to the engine.
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  • 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 daveson

  • ^ Quintessential Motobricker
  • Posts: 1268
Re: new k100rt idles for one minute, then stops
« Reply #9 on: January 11, 2019, 05:44:28 AM »
Hey everybody
We fixed the bike
What I did and the results :
Taped up exposed hall sensor cable... No go
Cleaned hall sensor connections... No go
Replaced hall sensor... No go
Cleaned earth's... no go
Replaced fuel and temperature relays... No go
Replaced load shed and horn relays... no go
Replaced computer...  She goes.
This bike had not been started in ten years
It now goes,  is much cleaner,  and I'm not afraid to tackle serious stuff like hall sensors any more.
Thanks all
That's one bike saved from the grave yard by motobrick. I wonder how many others have been.
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  • Victoria, Australia
  • Current; '85 K100RT~100,000km; four other bricks. Past; Vulcan 1500, V Star 650, KLX 250(dirt bike) TT250(dirt bike)

Offline The Mighty Gryphon

  • Administrator
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  • Posts: 6843
Re: new k100rt idles for one minute, then stops
« Reply #10 on: January 11, 2019, 08:57:40 AM »
Thank you for the good report on your troubleshooting.  Believe it or not, but feedback like yours is more valuable than whatever assistance we might offer.  It's how the forum improves it's database.
Logged
  • 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 natalena

  • ^ SuperNatural Motobricker
  • Posts: 742
Re: new k100rt idles for one minute, then stops
« Reply #11 on: January 11, 2019, 10:06:46 AM »
Congrats on the methodical, and successful result. Sure makes riding the brick that much more enjoyable, and something to talk about at rest points over a beer.
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  • MST
  • 1987 K75s #0919, '05 Sportster 1200C, '21 ARGO 8x8, '24 KLR650
"Hard to beat a 10x beaver, 'specially if you're gonna work it."

Offline KosmicK1100

  • Motobrick Curious
  • Posts: 23
Re: new k100rt idles for one minute, then stops
« Reply #12 on: January 11, 2019, 10:11:10 AM »
Nicely done daveson! That took a lot of patience and perseverance, nice to know another K bike lives to be enjoyed! The experience of troubleshooting is priceless and the rewards great!
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  • France, Germany
  • K1100RS

Offline KIWIDON

  • Curious
  • Posts: 6
Re: new k100rt idles for one minute, then stops
« Reply #13 on: January 13, 2019, 04:23:58 PM »
When you have spare time have a play with the old ECU as can often resurrect by opening up and running a soldering iron over the electrical plug wires where they connect to the circuit board. Just flow small amount of solder on each wire when heating, often it's a dry joint from years of use/harness replugging etc.
Always nice to have a free spare in stock, you might be lucky!
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  • AUCKLAND NEW ZEALAND
  • K75C, K75S, 61/65/68 T120, CAGIVA ELEFANT

Offline daveson

  • ^ Quintessential Motobricker
  • Posts: 1268
Re: new k100rt idles for one minute, then stops
« Reply #14 on: January 13, 2019, 04:32:02 PM »
Good one, thanks,  I'll look into it.
Logged
  • Victoria, Australia
  • Current; '85 K100RT~100,000km; four other bricks. Past; Vulcan 1500, V Star 650, KLX 250(dirt bike) TT250(dirt bike)
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