Author Topic: New old 1991 K100RS 4V  (Read 1701 times)

Offline riots100

  • ^ Proficient Motobricker
  • Posts: 136
Re: New old 1991 K100RS 4V
« Reply #25 on: July 26, 2018, 11:27:48 PM »
Shimmed up the rear ABS sensor, reset the ABS computer twice, ABS light extinguished.  Bike now has full functioning ABS I brakes.  (I didn't dare test the front though...)
  • Los Angeles, CA
  • 1992 K75, 2007 K1200GT, 1991 K100RS
----
BDJ

Offline mophead

  • ^ Motobrick Curious
  • Posts: 55
Re: New old 1991 K100RS 4V
« Reply #26 on: August 05, 2018, 02:03:01 PM »
Nice find.  The K1100RS bodywork will be hotter than the stock you have now.  Had one of these and it served me well.  Just service it and ride it.
  • Amarillo, TX
  • 95 K1100RS Formerly 86 K100RS & 91 K100RS
On the back nine of life

Offline riots100

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  • Posts: 136
Re: New old 1991 K100RS 4V
« Reply #27 on: August 06, 2018, 12:07:23 AM »

I added a mirror leash for the left side mirror.  The right side bracket had a missing mirror post, so I ordered a new one and am awaiting delivery.


(I hope to never see this while I am riding)

I flushed the rear brakes, added new stainless steel rear brakes lines and then bled the rear brakes.  The fluid in the rear reservoir was light colored and clean.  I flushed it anyway and you can see the debris that came out.





I pulled the tank back to get at the front brake line that goes from the front master cylinder to the hard line junction going back to the modulator in anticipation of installing the front stainless steel brake lines.  I noticed a few things about what's under this tank that I didn't have on my K75.

There are two overflow lines coming from the bottom of the tank.  One line just slips on a tube spigot coming from the bottom of the tank and goes drains to the rear master cylinder area. I assume that this is the line that drains fuel and water from the tank cap area.  The other line is held onto the tube spigot on the tank with a hose clamp.  That line then runs down to a one-way valve, then down to the same area near the rear master cylinder.  What is the purpose of this second drain line from the tank?



On pulling the tank back, I saw that there is large rubber grommet that goes between the tank and frame, and that the bottom of the tank had some thick, heat reflecting material glued on.  It looks like it came from the factory. (a factory Johnny blanket perhaps?)  There is also an empty plug that is circled, what purpose does this serve?



And now for the main issue.  The aforementioned brake line from the front master cylinder terminates at a junction into a hard line going to the modulator.  That junction is buried very deep in the wiring loom below the tank, and sits under the tank mounting brackets/grommets on the frame. It is very hard to get to with a wrench and can anticipate many difficulties in removing the old line and installing the new one.



Is there a better/easier method to get to this brake line junction?

As I am getting deeper into this bike, I am more amazed at how clean everything is and the "like new" condition of all the parts.  I am beginning to doubt that I am needing to even replace the brake lines. (despite the gunk that came out from the flushing of the rear lines)


  • Los Angeles, CA
  • 1992 K75, 2007 K1200GT, 1991 K100RS
----
BDJ

Offline riots100

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  • Posts: 136
Re: New old 1991 K100RS 4V
« Reply #28 on: August 09, 2018, 12:41:18 AM »
I finished up all the brake work.  I got the stainless steel lines on the front.  I put about 4-5 reservoir's worth of brake fluid through each system.  Hopefully that should be enough to have flushed the system. 





To get at the brake line junction under the tank, I had to remove the white retaining clamp that held down the two rigid lines to go to/from the modulator.  Then the line had enough play in it that I could get a wrench around each end.



Changed the oil with synthetic 20W-50. I'm going wait for the Eastern Beaver Headlight relay to come from Japan before I put the tank back in place.

  • Los Angeles, CA
  • 1992 K75, 2007 K1200GT, 1991 K100RS
----
BDJ

Online The Mighty Gryphon

  • ^ Quintessential Motobricker
  • Posts: 3821
Re: New old 1991 K100RS 4V
« Reply #29 on: August 09, 2018, 10:18:48 AM »
While the tank is off and you're waiting for the headlight relays you can wile away some time by adding a manual fan switch and maybe some LED driving lights to help the cagers see you.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '92K100RS White, '94 K75S Dakar Yellow
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'94 K75S "Cheetos"
'91 K100RS "Moby Brick Too

Offline riots100

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  • Posts: 136
Re: New old 1991 K100RS 4V
« Reply #30 on: August 16, 2018, 12:02:05 AM »
Got the bike back together.  I plan on installing aux driving lights, but I haven't decided where I want to mount them yet.  The common places seem to be on the lower forks, near the brake calipers or under the front fairing.  I will want to make any mounting look like it came from the factory.  The headlight relays are in and working.  The headlight seems a tad brighter.

The brakes feel the same but at least there is fresh fluid and new lines.  All the other rubber hoses look new and the bike runs like a champ.  Although, while riding around last night, I noticed that the instrument light for the fuel gauge is not working.  I assume that there is one, since I see the fuel temp gauge all lit up.

I'm going to do another shakedown ride along Mulholland Highway on Saturday.  I'm thinking that she is good to go and that I'll tackle other issues as they come up.
  • Los Angeles, CA
  • 1992 K75, 2007 K1200GT, 1991 K100RS
----
BDJ

Offline riots100

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  • Posts: 136
Re: New old 1991 K100RS 4V
« Reply #31 on: August 21, 2018, 12:31:21 PM »
Weekend shakedown ride complete.  The bike is in perfect working order. 

We went through a tank of gas in the Santa Monica Mountains and along the beach.

  • Los Angeles, CA
  • 1992 K75, 2007 K1200GT, 1991 K100RS
----
BDJ

Offline riots100

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  • Posts: 136
Re: New old 1991 K100RS 4V
« Reply #32 on: September 19, 2018, 01:06:49 AM »
After some normal freeway riding, I'm getting some fuel weep-age from the top of the fuel tank around the filler cap.  The days have been warm but not excessively hot.

telltale fuel trails emanating from the fuel cap.


The fuel would run down tank to the knee pads


Nothing like this has occurred with my K75.  I took off the filler cap and examined the area around the filler hole and the inside of the tank.  All the plumbing is correct and in good shape.  I did notice some powdery deposit deterioration between the fuel cap and the tank itself.  I wonder what could be causing this mild fuel leak?

My best guess at the moment is that the fuel vapor is making it past the gaskets in the filler cap and condensing back to a liquid state and running down the outside of the fuel tank and down the side of the bike.  Any other thoughts?

When I popped of the cap and looked inside, I did notice some corrosion of the metal on the inside of the tank.





corrosion around the sending unit


Are these areas of corrosion something that I should address?  And if so, what would be the best practice to remove this corrosion?
  • Los Angeles, CA
  • 1992 K75, 2007 K1200GT, 1991 K100RS
----
BDJ

Offline Laitch

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  • Posts: 5579
Re: New old 1991 K100RS 4V
« Reply #33 on: September 19, 2018, 06:28:34 PM »
. . . My best guess at the moment is that the fuel vapor is making it past the gaskets in the filler cap and condensing back to a liquid state and running down the outside of the fuel tank and down the side of the bike.  Any other thoughts? . . .
When I popped of the cap and looked inside, I did notice some corrosion of the metal on the inside of the tank.
Are these areas of corrosion something that I should address?  And if so, what would be the best practice to remove this corrosion?
Purchase a fuel cap gasket kit (16119062461] from BMW and replace the cap's internal gaskets. The gasket (16111453690) around the fuel tank cap opening is a separate component. Replace that after you've cleaned off the rim where it is mounted.

You could remove and clean the sender per robmack's technique.
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.

Offline riots100

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  • Posts: 136
Re: New old 1991 K100RS 4V
« Reply #34 on: October 01, 2018, 12:05:23 AM »
Finally received the fuel filler gasket set. The original parts had deteriorated with age and proximity to noxious fumes. This Video from Chris Harris helped quite a bit in getting the spring preload and positioning correct for assembly.






We'll see how well it works in fixing the fuel seepage problem with a full tank of fuel on a moderately warm day.  We should have plenty of those left here in SoCal!
  • Los Angeles, CA
  • 1992 K75, 2007 K1200GT, 1991 K100RS
----
BDJ

Offline natalena

  • ^ Motobrick Curious
  • Posts: 64
Re: New old 1991 K100RS 4V
« Reply #35 on: October 01, 2018, 11:16:50 AM »
Needed to mow the lawn ... so skipped that, and made a heat shield from a Domino's Pizza box and 3M 3350 aluminum tape. Rode around a bit, and by "the seat of the pants" measurements, it looks like the tadpoles are still swimming. Best part is, the board is covered on both sides with tape, so there's plenty to make a hat in case Chaos Inc. is trying to read my mind.

opps, sorry, meant for this to be under "what I did with my brick..." Damn interweb computee stuff.

*just reported myself to the moderators. Awaiting FBI investigation.
  • East of Joshua Tree
  • 1987 K75s #0919

Offline riots100

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  • Posts: 136
Re: New old 1991 K100RS 4V
« Reply #36 on: October 01, 2018, 12:22:30 PM »
No worries, I don't mind the thread hijack!

I'm guessing that this was to mitigate heat transmission through the seat?
  • Los Angeles, CA
  • 1992 K75, 2007 K1200GT, 1991 K100RS
----
BDJ

Offline natalena

  • ^ Motobrick Curious
  • Posts: 64
Re: New old 1991 K100RS 4V
« Reply #37 on: October 01, 2018, 08:31:05 PM »
No worries, I don't mind the thread hijack!

I'm guessing that this was to mitigate heat transmission through the seat?

Thanks for the forgiveness. Yep, it was very toasty this past summer with the engine heat funneling straight to the seat pan. Concept tested some R30 insulation which worked great (like the Johnny blanket), but was cumbersome to deal with. I'd guess the cardboard heat shield drops the "real feel" on the seat by at least 20f, enough where the heat isn't noticed at all.
  • East of Joshua Tree
  • 1987 K75s #0919

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