Originally Posted by Big Bamboo
Sounds like the return port on your master cylinder is plugged. Pull the cap off and look down at the bottom of the reservoir. You should see two tiny holes into the bore of the master cylinder. Use a toothpick or similar to clean them both.
That's my guess too. I have seen a rash of troubles caused in the last few years from the rubber hoses coming apart on the inside. Especially on oilheads for some reason but still . . . .