Some may remember the first rectangle-shaped brake master cylinders Kawasaki had back in 1979 and for a few years following. They were made of cheese and the piston bore would corrode and become pitted if not religiously maintained, meaning change of fluid every two years or better. Now Harley has run into a similar issue https://www.jsonline.com/story/mone...orldwide-because-brakes-could-fail/314581002/ There is a reason why I always strip the brakes when I buy old motorcycles. My brother has had two master pumps and one caliper fail instantly. Two at a standstill and once at low speed, so no harm done. But you certainly do not want the brakes to fail when you really need them.