'82 Kawasaki KZ750

When I press on the rear brake, it grabs and slows the bike, but when I lift my foot off the brake, it doesn't release. I have to pull the brake lever up with my foot and it will release.

In the attached pic you can see where the brake lever attachment point comes through the mounting bracket. I guess/hope that there is just road grime in there or that it just needs grease or somehting so that it can rotate. It's a real pain to get it through the hole in the mounting bracket because it's a real tight fit.

Guess my only real question is when a brake pump starts to or goes bad, is this a symptom? My uneducated guess is that if it were going bad, the only symptom is no braking power lol.

Attached Images

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I'm guessing those brake lines are done. Original? The brakes only squeeze, so if pressure stays after you release the brake, something is getting stuck. You can try to clean em, but if they are old, I'd just replace them and clean everything else.

Either your master cylinder is messed up, the pads are binding, the pistons are sticking, or the linkage is sticking.

If you can pull the lever up and it will stop braking, that to me sounds like a linkage issue not a Master or caliper issue. Clean it all up as best you can, check for any mangled bits, and regrease it and try it again.

Maybe the return spring is missing?

Return spring possibly. More then likely something is dirty, or bent. Tear it down and work the problem. The pivot for the brake arm is lubed and clean? The pistons in the caliper are clean? The seals are not hard and dry rotted around the caliper piston?