Motorcycle Repair: Honda 1981 GL 1100 front brakes lock up, caliper piston, rubber seal

Question
 I have been asked to look at a friend's 1100. The front brake (disc type) will lock up due to heat during riding       ( pads rubbing disc, not re-tracting ). He has released the brake by bleeding fluid. He has had brake rebuilt from one end to the other, still has problem. Brake fluid #3 is used in this system.

Answer
Here is the fix. What has happened is that the brake fluid has gotten behind the rubber seal that seals the caliper piston in the caliper.
Take the caliper off the bike and use the brake to pump the piston out of the caliper.Make sure that you keep the brake reservoir full of fluid.Any air wile pumping and it wont come out.After you have the piston out look inside and you will see a flat rubber ring inside the opening in the caliper.with a pick pry it out ( don't damage it )After it is out in the grove you will see a yellow hard substance, dried brake fluid.Use a small brass brush and get ALL of it out of the groove.You can use the rubber seal again but I recommend a new one I think Honda still sells them.Also check the piston ANY damage on the sides replace it Honda again.Put it back together making sure you lubricate ALL parts with brake fluid.DO NOT cock the piston when you put it back in.It has to go back straight, very little clearance.

Ride Safe  Jerry