I need some help.
The rear Master Cylinder on my 2012 Model X1200X seems to be leaking down the side of the cylinder at the cover. I first just wiped it off. I then noticed it continued, wiped it and removed the cover. The fluid seemed to be down about a small amount about an inch. I refilled and I am waiting to see if it continues. The brake is fine, the hole at the bottom was not exposed so I don't believe air ever entered the line. The MC has about 2K miles.
I inspected the cover and the plastic strainer both are OK. The reservoir has no cracks.
Does pressure ever build up to cause this? Has anyone experience this?
thanks,
Barrier

 

gasket kit

its like 5 or 6 bux tops -- run by dealer or get online - replace and see if the issue stops

as long as u see no cracks in the basket or cover then this should solve the issue

 

Re-build kit for the rear master cylinder. Part #42810-04B. As far as I know, that kit applies to a 2012, too, but verify.
Usually, the rear master cylinder takes a dump after changing rear brake pads or after simply removing/replacing the rear wheel. The instructions with the kit are pretty good. It's helpful to have a bench vise to perform the procedure.
My OL's '04 did it with 35,000 miles. When I swapped the pads on my '05, at about 20,000 miles, I cleaned the piston well, using a shoe string and brake clean, before pushing the piston back into the caliper's bore for the new pads' clearance. I didn't get the master cylinder failure on my '05 after replacing the brake pads. Maybe, I was lucky, and my cleaning procedure had nothing to do with it. Still, it's a good idea to clean the caliper/piston.

 

Thanks for the responses. I still wonder how a relatively new, low mileage bike could need a master cylinder rebuild? Is this common?
Any other thoughts?
Barrier

 

Bad gasket? Loose cap?
The part # I referenced is for a master cylinder re-build kit, not the reservoir. If your brakes work well, with no spongy feeling or lack of resistance, it's probably fine. Keep an eye on it (the reservoir), now that you've cleaned it and secured the cap.

 

I had the same problem.

It was because the cap was too tights when I checked the fluid level.

Take the cap off, check the gasket is seated, and screw the cap on, but not too tight!

 

This is a common issue with HD master cylinders..people think a little tight is good so more is better....just tighten the screws enough to keep the cover on but not so much as to squeeze the gasket out...

 

But this really isn't a master cylinder problem, it's a rear brake reservoir problem, they are two separate parts.

 

you must have great eye sight.....being able to split hairs like that..

 

I was only attempting to make clear that the rear brake reservoir and rear brake MC are 2 different parts, since several posters are advising rebuilding the MC and including part numbers for the rebuild kit. The MC is underneath the bike in front of the rear wheel. I suspect that rebuilding the MC is only going to be a waste of time and money based on the OP's described symptoms.