Front brake wont let go

So i had to break down my front caliper and rebuild it for this exact problem but now a couple months of riding a few times a week its back, any ideas on what would be causing my front brake to not let go?

It's the master cylinder there is a small bleeder hole in the master cylinder that releases the pressure. Sometimes that hole gets clogged.

Alright i will check there tomorrow.

I actually came for a similar problem, but since this topic is already up I'll just tag along...

In my case it's the back brake -- after two seasons of riding I've discovered my rear brake pads are completely shot, down to the metal on one side and almost there on the other. I started noticing a drag last week and figured out the rear brake wasn't releasing completely. My guess is that the drag causes the pads to heat up and drag even more, so I didn't notice it until I had ridden for a couple miles. I went to get gas this weekend (a few blocks away) and by the time I got home it was gripping so tight that I couldn't move the bike without giving it some throttle. I would assume the pads are worn out because of this recent problem.

So my question is, is there a similar bleeder hole somewhere in the rear brake system that could be partially clogged and not releasing quickly? Or would it be a different set of problems on the rear?

Yes all master cylinders have them. Be sure though that the brake lever is not hanging up allowing the brakes to drag.

A friend of mine had an ER-6N that got dropped and also had this issue. On that it turned out that the brake line from the master cylinder was kinked and thus would not flow. Make sure the brake line is not kinked.

Kawasaki calls for changing brake fluid every 10k miles or annually, whichever comes sooner. This is a little excessive but the point being brake fluid starts to coagulate and coat the inside of the lines, master, and the inside of the caliper with grunge that resembles jello so it's important to change it regularly. By the time that little port is plugged it's too late. A full system tear down is in order. Clean out the sludge and change the lines since they get soft with time and there is no way to clean them out anyway. Money well spent. If the caliper pistons are pitted they will need to be changed, and it's wise to change the seals too. Use OEM parts where ever possible. K&L brake system parts are junk so stay clear of them unless there is no other option.

Good luck

On rear brakes, another possibility is that the brake pedal pivot is rusted or packed with gunk, not letting the pedal return fully.

Nessism wrote: Kawasaki calls for changing brake fluid every 10k miles or annually, whichever comes sooner. This is a little excessive but the point being brake fluid starts to coagulate and coat the inside of the lines, master, and the inside of the caliper with grunge that resembles jello so it's important to change it regularly. By the time that little port is plugged it's too late. A full system tear down is in order. Clean out the sludge and change the lines since they get soft with time and there is no way to clean them out anyway. Money well spent. If the caliper pistons are pitted they will need to be changed, and it's wise to change the seals too. Use OEM parts where ever possible. K&L brake system parts are junk so stay clear of them unless there is no other option.

Good luck

Actually, that is 10,000 kilometers, not miles. More like 6,500 or 6,600 miles.

Thanks for all the replies. So a quick bit of history, the bike was completely tore down and rebuilt. The lines were completely drained during the rebuild and didn't get filled again until Spring of last year, but the fluid I drain out was pretty clean. I wasn't sure of a good way to flush the brake lines so I filled the reservoirs a few times and pumped all the fluid through (tossing the used fluid of course). I wouldn't be surprised if there had still been particles in the line though, which is why I thought the idea of a clogged bleeder hole sounded very plausible here. I didn't mention it before but after the bike sits for awhile the brake pedal loosens up again and the brakes feel like they are working normally again for a bit.

While the brake pedal does move smoothly, it certainly wouldn't hurt to pop it off and check the grease, but it does return all the way to the upper position by itself. It simply has a very limited -down- movement range after things heat up.

So where exactly do I find this bleeder hole in my system? And is it something I could push some fine piano wire through to try and unclog?

You can see it in the image below. The regular fluid passage is easy to see. To the left of that is what appears to be an indentation. In the bottom of that is the tiny return hole. Piano wire will be too big. You might be able to find a small enough guitar E string

laudeman.com/bmw_r850r/images/front_mast...ster_cylinder_14.jpg

How old are the lines? If old, they can be clogged with barnacles.