Author Topic: 1985 K100 speedo instrument cluster  (Read 542 times)

Offline warmas

  • Motobrick Curious
  • Posts: 45
1985 K100 speedo instrument cluster
« on: January 08, 2019, 12:15:53 AM »
Am in market for either, or perhaps just speedo/odometer circuit boards.
I electrically damaged something in it. Balance of cluster functions properly.
  • Enid, OK
  • 1985 K100 resuscitated, 1980 BMW R100, 1985 BMW R80

Offline Lumpy 1

  • Motobrick Curious
  • Posts: 12
Re: 1985 K100 speedo instrument cluster
« Reply #1 on: January 25, 2019, 01:14:59 PM »
Hi . i have a full cluster , removed from a 86 k 100 . Removed before i bought the bike so dont know any thing about it . Sure the rev counter needle is snaped off .. im in the UK
  • Sunderland
  • K100 cafe

Offline Andy FitzGibbon

  • ^ Motobrick Curious
  • Posts: 108
Re: 1985 K100 speedo instrument cluster
« Reply #2 on: January 25, 2019, 05:47:49 PM »
I have a box with a bunch of cluster parts. May have what you need. Can you email a photo to andrew.f@wildblue.net?

Andy
  • Montrose, WV
  • 1985 K100RS, 1972 R75/5, 2012 Suzuki DR650

Offline billday

  • ^ SuperNatural Motobricker
  • Posts: 999
Re: 1985 K100 speedo instrument cluster
« Reply #3 on: January 26, 2019, 10:30:25 AM »
The '85 cluster is no good -- in later years they added ventilation (two circular openings with fabric filters) on the back to prevent moisture buildup inside. Massive improvement. With all these guys going for aftermarket speedos on their kafe K-bikes, you can get a whole cluster for pretty cheap nowadays.

Like Andy said, if it's bits and pieces you want, you need to show up pictures.
  • New York State, USA 10977
  • 1985 K100

Offline warmas

  • Motobrick Curious
  • Posts: 45
Re: 1985 K100 speedo instrument cluster
« Reply #4 on: January 27, 2019, 10:34:39 AM »
Thanks for the replies.
I found an entire cluster, it has round pins and does fit my flat pin plugs, in real good shape, every function on it works, speedo and odo measure accurately, $55 shipped to me.

I previously had burned up the thermistor in the fuel level sender.
I replaced the thermistor with a 500 ohm thermistor from Mouser. The level light illuminated after 67 miles driven on a full tank. I think this has occured because the fuel has warmed.
Am unsure what my remedy is.
Ideas?
  • Enid, OK
  • 1985 K100 resuscitated, 1980 BMW R100, 1985 BMW R80

Offline Andy FitzGibbon

  • ^ Motobrick Curious
  • Posts: 108
Re: 1985 K100 speedo instrument cluster
« Reply #5 on: January 27, 2019, 11:15:40 AM »
The round pins don't always make good contact with the flat plugs, even though they do physically fit together. This is the reason that I have a box full of cluster parts...

Fuel heating/boiling on these bikes is a well-known problem. Search "Johnny blanket" or "K100 fuel cooler" for many different threads regarding the issue.

Andy
  • Montrose, WV
  • 1985 K100RS, 1972 R75/5, 2012 Suzuki DR650

Offline billday

  • ^ SuperNatural Motobricker
  • Posts: 999
Re: 1985 K100 speedo instrument cluster
« Reply #6 on: January 27, 2019, 08:21:10 PM »
$55? When I first got into K bikes, they were $255. So, life is getting better, right?

As far as the low fuel light: The whole system changed early on, so your newfangled cluster never will tell you the truth about your fuel level. Use your trip odo, while your enjoying having everything else work.
  • New York State, USA 10977
  • 1985 K100

Offline warmas

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  • Posts: 45
Re: 1985 K100 speedo instrument cluster
« Reply #7 on: January 28, 2019, 10:53:26 AM »
Life is definitely better.
Buying the replacement BMW K100 instrument cluster was much easier and cheaper for me than trying to figure out how to repair the original.

I haven't yet seen any evidence the newer cluster I have has a different fuel level light controller than the original cluster it replaced. They, externally and visually, are interchangeable. The round pins, to my surprise, make adequate contact with my flat pin receptacle.

The electronic fuel level light is, I have been told, a modern labor-saving upgrade to the archaic standard/reserve petcock fuel valve installed in duplicate on the few Airheads I own, whose fuel level is, as is here recommended for my K100, arithmetically deduced with the aid of the odometer.
Installation of external pump and filter and standard/reserve petcock  Airhead-style to a 1985 K100 would seem to simplify this whole mess? I see the most difficult step to be sourcing a petcock bushing for the fuel level sender port.

I have experienced the fuel heating and boiling events firsthand.
Thanks for the search terms.
  • Enid, OK
  • 1985 K100 resuscitated, 1980 BMW R100, 1985 BMW R80

Offline Martin

  • ^ Quintessential Motobricker
  • Posts: 3628
Re: 1985 K100 speedo instrument cluster
« Reply #8 on: January 28, 2019, 02:34:54 PM »
Last summer I experienced fuel vaporization in the fuel rail. This only occurred when in slow traffic on 30+C days with under 1/2 a tank of fuel.  These events caused stalling coughing and spluttering nearly resulting in being rear ended. I managed to measure the rail temperature a while after an event at 80C. Tried a home engineered fuel cooler which worked great at speed but not in traffic. I had a talk to a heat engineer and he confirmed my approach to stop the heat getting into the fuel rail. He stated it was better to prevent the problem from occurring than to try to fix it after it happens.

So I already had foam with double sided reflective coating fitted under the tank. I then insulated all the external fuel lines with foam sleeving and insulated the FPR with reflective tape. I then fitted an aluminium heat shield under the fuel rail backed with double sided reflective foam insulation. The end result so far has been a massive reduction in rail temperature which is now runninng below ambient temperature. Tank temperature so far is slightly above ambient temperature. In the next couple of weeks I am going to try the Brick with 1/3 of a tank of fuel out in heavy traffic which has been lacking due to school holidays. So far so good.

Regards Martin.
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  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline billday

  • ^ SuperNatural Motobricker
  • Posts: 999
Re: 1985 K100 speedo instrument cluster
« Reply #9 on: January 29, 2019, 11:20:31 AM »
Martin, so, I'm dense, but it's not clear to me what that rig does. Does it shelter the fuel rail from ambient heat? But doesn't it also trap in heat from the engine?

A few years back I got some pipe insulation from McMaster-Carr, I put it on the run from the tank to the fuel rail and also the return from the FPR to the tank. Had to buy six feet of the stuff, I bet I still have some to give away if anyone's interested.

Warmas, going to an external fuel pump will probably open you up to a whole new world of complications and woes . . . but the popcorn-munching mob on Motobrick will definitely enjoy watching the story unfold. Post lots of pictures!
  • New York State, USA 10977
  • 1985 K100

Offline Martin

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  • Posts: 3628
Re: 1985 K100 speedo instrument cluster
« Reply #10 on: January 29, 2019, 04:00:56 PM »
Bill it shields the fuel rail from the engine heat. Radiant heat from the engine can and is absorbed by the rail. BMW knew about this and on some models actually fitted the fuel rail with foam insulation. The shield is an extension of an old idea we used to use as teenagers to stop vaporisation. Old Holden's when hotted up and fitted with multiple carbs would suffer vaporization in the float chambers. To counteract it polished aluminium heat shields would be fitted between the carburettor and the manifold.  Since fitting the shield the highest temperature I have recorded on the rail is 40C where the highest recorded pre shield was 80C and well after a vaporization event. I have gone a bit further by fitting the double sided reflective foam. Sometime in the next couple of weeks I'll  give it the ultimate test and on a really hot day run it with a low tank of fuel.
Regards Martin
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline Martin

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  • Posts: 3628
Re: 1985 K100 speedo instrument cluster
« Reply #11 on: January 30, 2019, 08:00:50 AM »
A pump nearly identical to the OEM pump is available for external fitment.
Regards Martin.
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  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline alabrew

  • ^ Motobrick Curious
  • Posts: 88
Re: 1985 K100 speedo instrument cluster
« Reply #12 on: January 30, 2019, 12:44:16 PM »
Darn, Martin, have to wait couple of weeks for a really hot day? The news this morning showed 120F in Australia this week. How hot do you need it???
  • Alabama
  • 1985 K100, 1991 K100RS
Also:
2005 K1200LT
1979 R65
200,000 miles on BMW motorcycles

Offline Martin

  • ^ Quintessential Motobricker
  • Posts: 3628
Re: 1985 K100 speedo instrument cluster
« Reply #13 on: January 30, 2019, 02:50:34 PM »
Only expected 30C today and 28C -29C for the rest of the week. I at least want a 35C to put it to the test.
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

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