I have a 1980 XS1100SG and am having a problem with the rear brake. Sometimes I'll be sitting at a light with my foot on the rear brake and all of a sudden the pedal will lose pressure and sink all the way down. If I let go and push it again, all is ok....for a while then the same thing will happen.
I've bled the rear brakes multiple times, still does the same thing. Still seems to be losing pressure. I'm no mechanic but if there is a leak in the system allowing air to get it wouldn't the brake fluid be leaking out the same place? I see no evidence of brake fluid leaking at all.
Thanks to all.