Author Topic: Awakening 1987 K100RS from 10 year slumber.  (Read 3505 times)

Offline SpecialK

  • ^ Motobrick Curious
  • Posts: 81
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:

 [ Invalid Attachment ]

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

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

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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

  • ^ Quintessential Motobricker
  • Posts: 6711
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 K75T 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

  • ^ Motobrick Curious
  • Posts: 81
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.

 [ Invalid Attachment ]


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

  • ^ Quintessential Motobricker
  • Posts: 6711
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 K75T 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

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