K11 Owners Group

[jpberens1994K1100RS]

Looking at the front brakes last week end, thought they may be a bit thin.
Unbolted a caliper to take a better look. Side be side comparison with the new pads makes me think we have a very good safety margin yet.
Install a " Speed Bleeder " on each caliper. Take the cover off MC, siphon out the old DOT 4, use Q-tips & clean it all up real nice. Refill from a fresh bottle of DOT 4. Bleed out the system. All is well.
Next morning, head out to the garage, what's that under the bike? I don't remeber that spatter? Guess I overfilled the MC ? Clean it all up, even under the lever cover. Head off. Uh oh, very very small drip, then another ? WTF ? Turn around, ABS is working and brakes feel good & solid. All was well with the bleeders & the fluid, no corrosion or particulate in the fluid.
I wipe it all again & use a piece of dark cloth tie wrapped to the front of the MC, oh yes, it's weeping out the MC piston. Rebuild time I guess.
It was NOT leaking before I bled the system. Ordered the MC rebuild kit & got the piston. Need to know please is dressing the cylinder bore essential here for long term success? I was planning on using a rolled up piece of fine emory paper, or I can run to the auto parts store & get a brake cylinder hone to do it. Any thing else I gotta watch for here? We all know DOT 4 is very bad on paint, but besides that.
Thanks.
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1993 K1100RS that I'd rather be riding FAST!
2014 Moto Guzzi Norge

[tmarshall57]

I had a bad leak on the front m/c. I used a rebuild kit and dressed the interior of the cylinder with very fine emery paper until all pitting was removed and the interior surface was smooth. 1 year later and no problems.

On a similar note I removed the rear brake m/c when lubing the shaft splines. On reassembly the rear m/c leaked badly - I hadn't touched it!! A rebuild kit cured that problem also but why it suddenly started leaking I don't know - maybe the extra movement of the piston when bleeding the brakes causes borderline piston seals to fail.
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K1100RS Special Edition 1997
Arctic Silver/Black

[jpberens1994K1100RS]

Oh yeah!!!

That makes sense, the longer travel when bleeding the system could be just enough to make that marginal seal fail.

Thanks.
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1993 K1100RS that I'd rather be riding FAST!
2014 Moto Guzzi Norge

[chopper_harris]

I had similar issue during restoration, and was annoyed to find that the only available 'repair kit' was a full replacement piston, complete with seals.

So, instead of costing $5, it cost me $40 at trade from Venhill, the UK distrib for Magura.

Not good
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C1 200 (2001)
R100 RS (1990)
NSU Quickly N (1964)
Honda 400/4 F1 (1977)
MotoGuzzi 1000C (1978)
Suzuki TL 1000 R (1999)
Kawasaki KLV1000 (2005)
K12R Sport (2007) - Wifeys