So if you haven't gone down this worm hole. Here is some motivation as to why you should. Granted this Master Cylinder and Caliper were not the worst offenders that I have ever seen. These were parts that the Previous Owner rode daily and for about a month so did I. The whole time I was working on the brakes, The question in my mind was. How did this thing stop? First was to start with the caliper. Taking off the dust seal revealed that it was badly cracked. Although unfortunately in all my tries I could not get the picture to show it. But you can see the buildup of Brake fluid gunk on the inside of the seal, indicating that the Main seal was not sealing well as well. Also the main seal The "Gunk" in the Caliper was this lovely mess. Per RickCoMatic this is the result of water mixing with Brake fluid. So needless to say that all got rebuilt. Need I say more? So on to the Master Cylinder. Taking off the cover showed the seal is in sorry shape. Initial inspection of the piston showed something really wrong. In case you were wondering it is completely split in two. Further into the worm hole. The lovely mess that happens once the seal is broken. Do you really want all this getting into your brake fluid when you want to stop? What was left of the seal once it was torn free. The piston as it came out. And the piston, circlip and spring after they had been dried off. And finally the mess inside the MC Now like I said before. These are not the worst offenders out there and many on the forum probably have evidence of worse. But the fact still remains that had it not been for this forum I would have never thought to check this. And imagine what the result would have been in a panic stop? Check your brakes.