K11 Owners Group

[andytgriff]

I have a 96 K1100RS. Noticed a bit a brake fluid leak last summer. Looked under the cover at the bottom of the cylinder and there was fluid pooled there. bought and fitted a master cylinder repair kit but I think, after only 500 miles, that fluid is still leaking.

Has anyone experience of this or suggestions of other faults that I should investigate. Thank you

[Inge K.]

The front master is a bit unlucky design, as the piston sits very shallow in the bore.
And from the outer end of the bore also the corrosion starts which is the reason for starting a small leak,
then the brake fluid that have leaked out crystalizes and make it worse,
and the brake fluid then enters the boot which start to swell and then isn't able to keep the dirt and moisture out anymore.

Use very fine emery paper to make the outer part of the bore as smooth as possible and be careful to clean out all residues.
Fill the space between the piston and bore (after the piston have been mounted) with brake cylinder mounting paste.
Also leave a good amount just outside the piston/bore, this is to slow Down the corrosion as much as possible.
Also change the boot when overhauling the pump, as it swells when it comes in contact with brake fluid.

[Rafal]

Hello!
I would avoid abrasive paper - bits of abrasive material can sick in the housing alloy causing a lot of problems. Go rather for steel wool and polishing paste on kind of soft cloth or small painting roller.

Best regards,
_________________
Rafal
K1100RS is a real beast (in Marrakesh Red)
K75S is a real beauty - she has gone , but not to far .

[abreeze]

IMO..just replace the whole thing. Beemerboneyard.com has them for a resonable price.

If you must clean it, ive found using a fine glass bead blaster is the best way to hone the cylinder Without taking off any material.