Motorcycle Repair: 78 goldwing 1000, brake cylinder, master cylinder

Question
my rear brake will engage on its own whats up with that any ideas why

Answer
The brake may be stuck on slightly, heating up the fluid which makes matters worse.  I would clean the brake cylinder, especially the seal on the piston and behind it since corrosion builds up behind the seal. Chnage the fluid, and check that the return orifice in the rear master cylinder is clear.  Hope this helps,  Jan