Hello, This is my first post here. I have a 1990 Yamaha XT350 that I am slowly rebuilding to its former glory. I am in the process of replacing the piston and rings along with a valve lap and shim. Here is my problem. I replaced the brakes front and rear. After installing the new front disk pads I bled the caliper but could never seem to get the air out. I rode the bike a few times and when the caliper would heat up, the expansion would clamp down on the disk. The only way to remove the pressure was to open the bleeder. I am assuming I have gotten something in the master cylinder and it is not letting the built up pressure to return back from the caliper. I have even tried to use a c-clamp to push the caliper back and it will not go. I am going to have to buy rebuild parts I know but my question is this. Is there a port that can get blocked in the master cylinder to cause this problem? Thanks for the help.