Author Topic: Surging Brick  (Read 12623 times)

Offline mophead

  • ^ Motobrick Curious
  • Posts: 104
Re: Surging Brick
« Reply #25 on: April 09, 2018, 10:16:27 PM »
On my last ride I headed into a 20 mph head wind.  Bike ran fine with no surging for 20 miles into the wind.  Turned south onto another road and then had a side wind.  Bike started to surge again although not as bad as before.

Turned bike back toward home which gave me the 20 mph tailwind and bike started surging even more.  Could get it to 110 but surging even more.  Dropped back down to 70 mph and stumbled back home.  Bike idles fine now so thinking after setting TPS to correct setting the computer learned and returned the idle to normal.

Ambient temperature was 68 degrees F.  Could the temperature sensor be going bad making for a rich fuel mixture that causes the surging?  Extra cooling going into the headwind ran fine and less cooling with the tailwind and rough running.
  • Amarillo, TX
  • 95 K1100RS Formerly 86 K100RS & 91 K100RS
On the back nine of life

Offline The Mighty Gryphon

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Re: Surging Brick
« Reply #26 on: April 09, 2018, 11:46:40 PM »
Any problems with starting a warm engine?  I would think a bad temperature sensor would make the mixture too rich for starting when the engine is warm, possibly flooding it.  I can't recall if there is a fault code for a bad temperature sensor.

It is beginning to sound to me like the problem could be related to a throttle setting.  I believe the throttle position sensor for the Motronic system is a potentiometer with a wiper travelling over a resistance element, and as such could have a dead spot.   Without knowing what is inside I can't suggest a test, but the idea would be to see if there is a smooth continuous change in resistance as the throttle is opened.  With your problem, I would expect to see the resistance jump at the throttle position where the surging is occurring. 

Slowly opening and closing the throttle with an analog meter connected to the TPS output should show if there is a noisy pot in the throttle position sensor.  Can't say which pins on the sensor you need to connect to.
  • 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 Laitch

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Re: Surging Brick
« Reply #27 on: April 10, 2018, 12:34:07 AM »
I can't recall if there is a fault code for a bad temperature sensor.
Old age does that. :giggles

Anyway, here's a post with more Motronic codes, pin numbers and other relevant detritus which might help. The author indicates it applies to a '93 K11 but could apply to later models, too. ¿Quién sabe?
  • 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.
https://tinyurl.com/RillRider

Offline bizzaro

  • ^ SuperNatural Motobricker
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  • co pilot
Re: Surging Brick
« Reply #28 on: April 10, 2018, 05:50:50 AM »
 :hide
  • Vermont
  • Current:1994 BMW K1100LT Previous: 1982 Yamaha virago 920,1973 Honda CB550,1976 Yamaha 650 Special
See Ya in the Twisties,
 Bizz

Offline mophead

  • ^ Motobrick Curious
  • Posts: 104
Re: Surging Brick
« Reply #29 on: April 10, 2018, 02:02:20 PM »

Gryph,


I like the idea you put forward.  To answer your question it is not hard to start when warm.  I'll do some research and see if there is any info on which pins to connect to.  When I adjusted the TPS earlier I was just checking for the required voltage which was off by the way.
The bike has been very difficult to start through all this scenario.  Since setting the TPS and riding it for a few miles it now has started right up on cold start where before it would not.  What is strange when it did not want to start I would hit the starter time and time again and no start.  Come back 30 minutes later and it would fire right up first bump of the starter. 

  • Amarillo, TX
  • 95 K1100RS Formerly 86 K100RS & 91 K100RS
On the back nine of life

Offline rbm

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  • Regards, Robert
Toronto, Ontario

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

Offline The Mighty Gryphon

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  • Posts: 6617
  • 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 mophead

  • ^ Motobrick Curious
  • Posts: 104
Re: Surging Brick
« Reply #32 on: April 11, 2018, 10:32:39 AM »

Info on TPS internals and troubleshooting Bosch Motronic on a K1100.


Thank you Robert!!  Will be checking some of these resistance measurements later and maybe find the culprit.
  • Amarillo, TX
  • 95 K1100RS Formerly 86 K100RS & 91 K100RS
On the back nine of life

Offline mophead

  • ^ Motobrick Curious
  • Posts: 104
Re: Surging Brick
« Reply #33 on: April 11, 2018, 10:37:28 AM »

Here's a list of some symptoms of a bad TPS:

https://repairpal.com/throttle-position-sensor

If you need to replace it, here's a good one on eBay:

https://www.ebay.com/itm/BMW-R1100R-13631461852-Throttle-Body-Position-Switch-k1100rs-k1200gt-k1200lt/112370665060?hash=item1a29d04664:g:hpoAAOSwc-tY8Qcl&vxp=mtr


Thank you sir.  Going to check out some of the measurements Robert's info suggests and might have to get on that TPS. 
  • Amarillo, TX
  • 95 K1100RS Formerly 86 K100RS & 91 K100RS
On the back nine of life

Offline The Mighty Gryphon

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Re: Surging Brick
« Reply #34 on: April 11, 2018, 12:18:40 PM »
Let's hope this gets it.  Riding season is upon us.
  • 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 mophead

  • ^ Motobrick Curious
  • Posts: 104
Re: Surging Brick
« Reply #35 on: April 11, 2018, 06:44:21 PM »
Got all excited about Roberts post and resistance measurements included in the link.  TPS check between pins 31 and 25.  Don't have a pin 25 so guess a different Motronic  There were several more checks where I didn't have the pins called for.

Last two days bike has started easily.  Now back to no start without grinding on starter then going back later to have it start.  All I did was change the battery and the current one shows 13+ volts after recharging with battery tender.  This thing is killing me.

I have searched for the meaning of 2343 code, mixture is at limit.  Cannot find how to dial down the mixture assuming it means fuel mixture which I'm not sure that is what it means.
  • Amarillo, TX
  • 95 K1100RS Formerly 86 K100RS & 91 K100RS
On the back nine of life

Offline johnny

  • TrailBrakingThrottleWhacker
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Re: Surging Brick
« Reply #36 on: April 11, 2018, 08:13:18 PM »
greetings...

i dont know however im thinking it maybe the o2 sensor in the exhaust... id disconnect it and start it and see if it behaves the same...

if me... this next... if that aints it id check to make sure all grounds are clean and tight at the battery and their terminations...

j o

  • :johnny i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin  :johnny

Offline mophead

  • ^ Motobrick Curious
  • Posts: 104
Re: Surging Brick
« Reply #37 on: April 11, 2018, 09:50:39 PM »
Thank you Johnny.  I'll try that out tomorrow.
  • Amarillo, TX
  • 95 K1100RS Formerly 86 K100RS & 91 K100RS
On the back nine of life

Offline mophead

  • ^ Motobrick Curious
  • Posts: 104
Re: Surging Brick
« Reply #38 on: April 23, 2018, 07:10:50 PM »
Johnny, bike will not start with o2 sensor disconnected.  Will start with it connected then dies when you unscrew the connector.  Any more ideas?
  • Amarillo, TX
  • 95 K1100RS Formerly 86 K100RS & 91 K100RS
On the back nine of life

Offline mophead

  • ^ Motobrick Curious
  • Posts: 104
Re: Surging Brick
« Reply #39 on: May 08, 2018, 09:59:20 AM »

It is with great reluctance that I post this.  The Brick does not surge anymore.  It runs perfect just like it did before all this fiasco started.  Apparently the bike likes to have ALL the ground wires connected to the battery.  When reinstalling the battery I let one get lost in the innards and overlooked it.  TWICE.  I disconnected the battery one more time and reconnected the wiring to it just to be sure I had everything done properly.
Was about to go after the temperature sensor with all the body work off and down amongst the coolant recovery tank there was this wire that was not connected to anything.  Hmmm, looks like it should go on the negative battery post.  Took out the battery bolt, hooked it up, ran like a top.  Went a couple hundred miles Sunday and all is well.


Feel free to declare the Mophead Dumbass of the Year.   :eek: :hehehe
  • Amarillo, TX
  • 95 K1100RS Formerly 86 K100RS & 91 K100RS
On the back nine of life

Offline The Mighty Gryphon

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Re: Surging Brick
« Reply #40 on: May 08, 2018, 07:05:44 PM »
You aren't the first...
  • 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 mophead

  • ^ Motobrick Curious
  • Posts: 104
Re: Surging Brick
« Reply #41 on: May 08, 2018, 07:24:02 PM »
Gryph, you are so very kind!
  • Amarillo, TX
  • 95 K1100RS Formerly 86 K100RS & 91 K100RS
On the back nine of life

Offline gone_ape

  • ^ Proficient Motobricker
  • Posts: 135
  • 94 K75RT (Now Standard)
Re: Surging Brick
« Reply #42 on: May 08, 2018, 09:24:37 PM »
I think everyone here has one of those moments.  And therefore we're all in the club d'nimcompoop.  Fuel pump test with eventual Tank removal for example.... Non-Runner Non-Starter....Even after reading/studying everything I could on what you must and then must not do I still got it wrong by forgetting....errrrrrr leaving one stupid process out....that would be "plugging the tank connector together"...Welcome to the club.....
  • Austin, TX
  • 94 K75RT (Now Standard)

Offline stokester

  • ^ SuperNatural Motobricker
  • Posts: 802
Re: Surging Brick
« Reply #43 on: May 08, 2018, 11:03:15 PM »
We've all been there.


Now it's time to ride!  :curvy-road
  • Yorktown Virginia
  • '94 K75S Dakar Yellow - '93 K75S Seiden Blau - '91 R100RT Bermuda Blue- '78 R100S Smoke Red

Offline The Mighty Gryphon

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Re: Surging Brick
« Reply #44 on: May 10, 2018, 08:29:59 AM »
Put the clutch together.  So nice, everything torqued, walk over to the workbench, look down...

...Clutch O-ring.
  • 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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