Author Topic: Awakening 1987 K100RS from 10 year slumber.  (Read 5024 times)

Offline SpecialK

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  • Posts: 98
Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #150 on: August 14, 2019, 09:20:32 PM »
If the master cylinder is off of the bike and disconnected from the brake line, you can dissolve the crystallized brake fluid by a short soak in hot water.  After the parts separate, dry them off and blow any remaining water off with compressed air.

I soaked the parts in soapy hot water but nothing was coming apart. I ended up putting the housing in a vice and clamping a channel lock plier onto the plunger end and turning. After much marring and trying to twist it finally started to turn and I could hear the spring turning but it took some twisting and tapping the pliers for it to come out. the inside of the cylinder looks clean but hard to tell.  I am soaking for a while the see if it will clean up.
The plunger/spring looks good except the tip where the pliers scraped it up. How does it go back in though? does the other end where the hose screws in come out?
I think I have four options; get the retro fit from China, Buy the rebuild kit for $67, buy a whole new master cylinder assembly from MAX for $152, or try to reuse what I have.

Now that I am looking at the photos, the MC doesn't look to be in good condition so may have to go the Chinese or new OEM route:


* fullsizeoutput_3833.jpeg (30.05 kB . 613x576 - viewed 110 times)

Marred up tip. Not good. Little plate on the end of the plunger insert came off.


* fullsizeoutput_3835.jpeg (26.94 kB . 676x576 - viewed 112 times)

Is inserting to the left the only way for this to go in? The taper on the plunger bushings is against the grain.


* fullsizeoutput_3834.jpeg (19.43 kB . 768x335 - viewed 111 times)

Thanks for you help.
  • Wappingers Falls, New York
  • 1987 K100RS
"The first to present his case seems right, till another comes forward and questions him". Proverbs 18:17

Offline Laitch

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Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #151 on: August 14, 2019, 10:58:45 PM »
A moment of clarity has revealed to me that for a brake cylinder to be a master cylinder, it must control a slave cylinder. These motos only have one front brake cylinder and one rear brake cylinder.

Anyway, your rear brake cylinder parts are junk when viewed from where I sit on the porch of The Ridley Brook Butterfly and Hummingbird Preserve Gun Club. I recommend replacing the entire rear brake cylinder assembly and also replacing the brake fluid reservoir with a cylindrical container that can hang on a frame member beneath the right side cover away from the effects of sunlight on its integrity.
  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline SpecialK

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  • Posts: 98
Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #152 on: August 15, 2019, 01:03:51 PM »
A moment of clarity has revealed to me that for a brake cylinder to be a master cylinder, it must control a slave cylinder.

Yes but if there is no slave then the Master is truly a Master. Maybe of his own destiny, or maybe he's the Master of the brake hose? Anyway, the Fiche calls it a rear brake master cylinder.


* Rear Brake Master Cylinder.JPG (33.5 kB . 537x399 - viewed 104 times)


Anyway, your rear brake cylinder parts are junk when viewed from where I sit on the porch of The Ridley Brook Butterfly and Hummingbird Preserve Gun Club. I recommend replacing the entire rear brake cylinder assembly and also replacing the brake fluid reservoir with a cylindrical container that can hang on a frame member beneath the right side cover away from the effects of sunlight on its integrity.

Those suggestions sound wise and in line with what I am planning. Thanks
  • Wappingers Falls, New York
  • 1987 K100RS
"The first to present his case seems right, till another comes forward and questions him". Proverbs 18:17

Offline Laitch

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Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #153 on: August 15, 2019, 01:12:15 PM »
Yes but if there is no slave then the Master is truly a Master. Maybe of his own destiny, or maybe he's the Master of the brake hose?
Nonsense. It's Germglish run amok.
  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline SpecialK

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  • Posts: 98
Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #154 on: August 22, 2019, 07:57:44 PM »
Received the master rear cylinder rebuild kit. The cylinder bore cleaned up nicely with 0000 steel wool so I went ahead and ordered the kit. Also have the calipers off so will check all of them and bleed the brakes when I get back from Maine on the 28th.
  • Wappingers Falls, New York
  • 1987 K100RS
"The first to present his case seems right, till another comes forward and questions him". Proverbs 18:17

Offline SpecialK

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  • Posts: 98
Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #155 on: August 30, 2019, 05:43:53 PM »
I am off to a slow start getting back to the K100 project after vacation but this Labor Day weekend should be productive. One issue I need to start attending to is the right front turn signal. It has some light scrapes that look like from a drop at some point and someone must have botched the wiring when repairing.
I did check the wiring diagram but it is hard to see the color codes. Can someone tell me from the two photos what I need to do to reconnect and get working? Obviously one connector on the black wire is missing. Do I need to splice a new connector on?

Thanks.

Fairing wires

* IMG_0002.JPG (38.7 kB . 768x576 - viewed 79 times)

Wires from right unit

* IMG_0004.JPG (77.99 kB . 768x576 - viewed 78 times)
  • Wappingers Falls, New York
  • 1987 K100RS
"The first to present his case seems right, till another comes forward and questions him". Proverbs 18:17

Offline johnny

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Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #156 on: August 30, 2019, 07:41:59 PM »
greetings...

that is not oe... are both the left and right side turn signals wiored the same...

no telling what has happened here... mirror mounted driving lights... could be anything...

you are gonna have to test those with a meter... key off key on flasher off flasher on... you getts the idear...

the mirror signal connector only slides in one way... its the white one...

the other connector... the black one... gonna have to trace those wiors back to the hot ground switch if any to figger that out...

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

Offline Laitch

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Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #157 on: August 30, 2019, 09:02:18 PM »
Blue/Black and Brown wires. Blue/black runs to the flasher unit, brown to ground.
  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline SpecialK

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  • Posts: 98
Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #158 on: August 30, 2019, 10:46:30 PM »
Blue/Black and Brown wires. Blue/black runs to the flasher unit, brown to ground.


Thanks, mine was pixelated so I couldn't read it. It would seem then there should be a blue/black/brown connector on the blinker housing instead of a bare black wire and a brown wire with a connector.
  • Wappingers Falls, New York
  • 1987 K100RS
"The first to present his case seems right, till another comes forward and questions him". Proverbs 18:17

Offline SpecialK

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  • Posts: 98
Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #159 on: September 02, 2019, 09:48:57 AM »
It would seem then there should be a blue/black/brown connector on the blinker housing instead of a bare black wire and a brown wire with a connector.

Thanks Laitch for the diagram. After further examining of the mirror/blinker assembly, I noticed a plug socket that takes the blue/black and brown wire. So the black and brown wires are extra and run to an inserted bulb installed by the PO (see photo). The bulb is not attached and is just laying in the housing so I can take it out easily. The blue/black/brown on the right, and blue/red/brown on the left were not plugged in when I removed the mirrors, just the extra white/brown wires running to the extra bulb were connected.

My two questions would be:
-What was the purpose of that extra bulb? Heat the mirror?
-Do I need to trace back and remove the extra white/grey leads that run into the fairing or can I just leave them there?

extra bulb

* fullsizeoutput_3868.jpeg (42.36 kB . 768x576 - viewed 64 times)

black/brown wire to extra bulb

* fullsizeoutput_386a.jpeg (40.46 kB . 728x576 - viewed 64 times)

fairing with stock blue/red/brown wire and extra white/grey wire

* IMG_0003.JPG (40.41 kB . 768x576 - viewed 64 times)
  • Wappingers Falls, New York
  • 1987 K100RS
"The first to present his case seems right, till another comes forward and questions him". Proverbs 18:17

Offline johnny

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Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #160 on: September 02, 2019, 10:07:23 AM »
greetings...

rodger that... i use heated grip elements to heat my mirrors...


* symtec_heated_mirrors.jpg (33.39 kB . 576x576 - viewed 65 times)

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

Offline SpecialK

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  • Posts: 98
Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #161 on: September 02, 2019, 10:25:52 AM »
greetings...

rodger that... i use heated grip elements to heat my mirrors...


* symtec_heated_mirrors.jpg (33.39 kB . 576x576 - viewed 65 times)

j o

So you think those little bulbs were to heat the mirrors? Much simpler system than yours.
  • Wappingers Falls, New York
  • 1987 K100RS
"The first to present his case seems right, till another comes forward and questions him". Proverbs 18:17

Offline johnny

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Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #162 on: September 02, 2019, 11:08:40 AM »
greetings...

of course... why else would somebody putts a heat source in there...

look... if you not running heated grips... heated mirrors... heated peggs... heated seat... and remote start in and abouts the hudson river watershed then you just whack...

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

Offline SpecialK

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Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #163 on: September 02, 2019, 11:32:07 AM »
Haha, I guess you do have a point!


  • Wappingers Falls, New York
  • 1987 K100RS
"The first to present his case seems right, till another comes forward and questions him". Proverbs 18:17

Offline SpecialK

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  • Posts: 98
Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #164 on: September 02, 2019, 01:57:46 PM »
Update:

I hooked the blue/black/brown and blue/red/brown back up and now the turn signals work fine but I have no parking lights.

On another note, I was just trying to get the rear wheel off to check the splines. The caliper is off and now I am trying to break the (4) 17mm bolts that hold the rim on with no luck so far. I have a cheaper set of sockets and the extension started to twist. Should I get a better 17mm socket and a breaker bar or can the final drive unit be taken out with the tire on? I don't want to twist off any bolts.
  • Wappingers Falls, New York
  • 1987 K100RS
"The first to present his case seems right, till another comes forward and questions him". Proverbs 18:17

Offline johnny

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Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #165 on: September 02, 2019, 02:11:52 PM »
greetings...

you gotts the oe tool kit with the lug wrench and extension...

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

Offline SpecialK

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  • Posts: 98
Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #166 on: September 02, 2019, 02:23:43 PM »
Thanks jo, yes I have it. Didn't think to try that, figured the socket wrench would do....
  • Wappingers Falls, New York
  • 1987 K100RS
"The first to present his case seems right, till another comes forward and questions him". Proverbs 18:17

Offline Laitch

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Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #167 on: September 02, 2019, 02:36:09 PM »
I hooked the blue/black/brown and blue/red/brown back up and now the turn signals work fine but I have no parking lights.

Should I get a better 17mm socket and a breaker bar or can the final drive unit be taken out with the tire on?
Come on now. You need to remove the wheel so you'll be able to put a new tire on it in the future. Are you going to drag the final drive along with you to get a tire mounted? That will provided amusement for the mechanic, certainly.

You need to learn how to remove seized bolts. Heat them with a heat gun or torch, add Liquid Wrench, rap on them with a hammer a few times, wait a couple of minutes then put the torque to them. A breaker bar or extension will help as johnny indicates.

The parking light wires are a grey-white wire and brown wire.
  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline SpecialK

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  • Posts: 98
Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #168 on: September 02, 2019, 03:56:26 PM »
Come on now. You need to remove the wheel so you'll be able to put a new tire on it in the future. Are you going to drag the final drive along with you to get a tire mounted? That will provided amusement for the mechanic, certainly.

The simplest solution worked as recommended by Johnny. I used the tool kit lug wrench with a short pipe.
  • Wappingers Falls, New York
  • 1987 K100RS
"The first to present his case seems right, till another comes forward and questions him". Proverbs 18:17

Offline SpecialK

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  • Posts: 98
Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #169 on: September 02, 2019, 04:28:00 PM »
Got the rear wheel and final drive section removed. I have not done this before but from what I have read and seen the splines look good with no "steps". The grease in there was brownish red.

See before and after cleaning photos:

Rear section before

* IMG_0002.JPG (71.21 kB . 768x576 - viewed 58 times)

* IMG_0013.JPG (46.67 kB . 768x576 - viewed 58 times)
Rear section after

* IMG_0007.JPG (63.95 kB . 768x576 - viewed 60 times)

* fullsizeoutput_3874.jpeg (56.9 kB . 768x576 - viewed 59 times)

Drive shaft section before

* fullsizeoutput_3872.jpeg (40.85 kB . 624x576 - viewed 59 times)

* IMG_0004.JPG (45.59 kB . 768x576 - viewed 58 times)
Drive shaft section after

* fullsizeoutput_386d.jpeg (49.37 kB . 756x576 - viewed 58 times)

* fullsizeoutput_3870.jpeg (38.48 kB . 633x576 - viewed 59 times)

  • Wappingers Falls, New York
  • 1987 K100RS
"The first to present his case seems right, till another comes forward and questions him". Proverbs 18:17

Offline johnny

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Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #170 on: September 02, 2019, 05:05:55 PM »
greetings...

i wept because i had no techron until I met a man who had no radials...

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

Offline SpecialK

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  • Posts: 98
Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #171 on: September 07, 2019, 04:30:58 PM »
Spent the day Friday on the rear splines and brakes. lubed the splines and reinstalled the rear drive. Used Enduralst molybdenum based grease from EME. Took apart the rear caliper and cleaned then using the new rebuild kit rebuilt the rear brake cylinder and reassembled everything onto the footpeg plate and attached. When I removed the main bolts that hold the caliper to the rear drive, I striped one of them. I went to MAX a picked up a new set. The new caliper bolts are 50 Torx, not 6mm hex like the originals. Put new DOT 4 fluid in and bled the brakes. The brakes are working properly now.

I then proceeded to drain and bleed the front brakes with new fluid. These brakes were working when I bought the bike but I wanted to change the old brake fluid. After I started messing with bleeding I noticed brake fluid seeping from under the reservoir. Looks like a tear down and cleaning of the front brake cylinder is in order. According to the section Johnny posted on brakes and Frankenduck's comment, I may be able to get away with just cleaning instead of a rebuild.

So now most of the main issues are resolved and the bike is getting near inspection status.


Rebuilt Rear Cylinder

* IMG_0009.JPG (57.11 kB . 768x576 - viewed 41 times)

Old cylinder parts

* fullsizeoutput_3882.jpeg (48.09 kB . 676x576 - viewed 41 times)
  • Wappingers Falls, New York
  • 1987 K100RS
"The first to present his case seems right, till another comes forward and questions him". Proverbs 18:17

Online Martin

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Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #172 on: September 07, 2019, 05:40:42 PM »
The rear brake master cylinder is subjected to a lot of road crap and water. A boot in good condition is critical to it's well being. As an extra precaution and to stop corrosion, I pack thick silicone grease under the boot to stop the ingress of water and crap. As an aside it seems to stop the boot from degrading.
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline SpecialK

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Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #173 on: September 07, 2019, 08:17:08 PM »
The rear brake master cylinder is subjected to a lot of road crap and water. A boot in good condition is critical to it's well being. As an extra precaution and to stop corrosion, I pack thick silicone grease under the boot to stop the ingress of water and crap. As an aside it seems to stop the boot from degrading.
Regards Martin.

Hi Martin. I remember you saying this back a few weeks ago. Sounds like good PM for the cylinder. I noticed the new boot that came with the rebuild kit was quite a bit smaller than the original. I didn't know if I could get it over the cylinder but managed to. At first I thought maybe the old one was stretched out but I'm thinking maybe they made it fit tighter to prevent road crap from getting in.
  • Wappingers Falls, New York
  • 1987 K100RS
"The first to present his case seems right, till another comes forward and questions him". Proverbs 18:17

Online Martin

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Re: Awakening 1987 K100RS from 10 year slumber.
« Reply #174 on: September 07, 2019, 11:22:12 PM »
SK silicone grease is very useful on Bricks. I last changed my fork seals twenty years ago just after I got it. I pack the space between the seal and dust cover with heavy silicone grease and change it every couple of years. It keeps the dust dirt and road crap from getting into the seals. I'd change it more often in dusty conditions or fit gaiters. I also use it around electrical connectors to stop air and moisture getting in. I've only ever had electrical connector problems with the infamous 4 pin fuel pump connector and the temperature sensor connection twice. The temp sensor connection was due to it not being greased due to it being hard to get to. It is now greased and no problem since. I am currently running a Chicom rear master cylinder, but my 26 year old OEM one is still in perfect condition with no corrosion.
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

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