Motorcycle Repair: brakes locking up, caliper pistons, pressure control valve

Question
I have a 1988 gl1500 with a motor trike kit installed. And lately I have had first, my rear left brake start dragging, it has happened twice on the left side then once on the right side. The last time I tried to ride it the left disk on the front started to do the same thing. And it got hot enough to almost lock up on me before I got turned around and back to the house. I am sure I will have to replace the front disk and probably the pads as well. Any ideas on how this is happening and keeps moving from one wheel to another?

Answer
Joe,

-this is almost certainly the master cylinder
relief hole plugged. It lets the fluid flow
back to the reservoir when the brake is released.

here are some other possible problem areas:

-the pressure control valve stuck.
(built into the rear GL1500 master cylinder)

-plugged or collapsing brake lines.

-residue buildup around banjo bolts.

-sticky caliper pistons.

-caliper sleeve or slide pins on mounting bolt seized.

-sticky brake lever pivot.

-You will have to clean the master cylinder well
to make sure the relief hole is open and
check for a good clean flow of brake fluid
right to the calipers. Even tiny bits
of dirt can build up over time and plug
the lines, calipers etc.

-If you clean the master cylinder for the rear
brakes well, the pressure control valve
is within and not serviceable but will
benefit from the cleaning.

-brake lines may need to be physically cleaned out
or replaced if bad.

-the rear brake pedal master cylinder also
controls the front left caliper which you said got stuck
as well.