R65LS Front Brake Problem

[chrisR65LS]

I have a '84 R65LS with a front disc brake problem. This bike is only rode approximately once or twice a week. I purchased this bike in June and have experienced this brake problem twice. The front brake acts as though pressure is building up in the system causing the brakes to start to drag eventually locking the front wheel. Both times I relieved the pressure from one of the bleeder screws on the caliper and they immediately released. The first time this happened I rebled the brakes and each time I rode the bike afterwards I could tell the brake lever was getting less free play. Today this problem happened for the 2nd time since buying the bike. In less than 1 mile I could feel the front brakes start to drag and as soon as I could get to a safe spot to stop the brakes were so tight that the bike could not be pushed. I just slightly opened the right side bleeder and it immediately released. I was warned of this from the fellow I bought it from. He thought the fluid was absorbing moisture causing the problem. Does anyone have any ideas what is causing this to happen and a good solution to fix it. It has stock Brembo calipers.

[AntonLargiader]

This is actually an easy one. Common on non-maintained Airheads but other bikes also. I had an R1100RS come in, crashed, for this.

The bleed hole (aka return port) in the master cylinder is clogged. Take the cover off and look in; you'll see a tiny hole and probably a larger hole as well. The tiny one is clogged and as the fluid heats up it can't flow into the MC to equalize pressure.

As soon as you squeeze the lever, the seal crosses that hole so fluid won't escape out when you're trying to brake.

Take a pin and clear the hole. You might need to remove the MC to get at it.

[chrisR65LS]

Thanks!! I will check the master cylinder tomorrow.