While working on my master cylinder ,I came across an odd situation that I thought I'd share. My new master cylinder had two holes communicating with the main reservoir. The smaller of the two didn't seem to go all the way through however. in checking with the old cylinder I had just removed, I found the same thing, what appears to be a 1/8 hole drilled, but not all the way through. In reading the new book so helpfully provided by Steve A. there is a passage to be sure and pass a wire through the small relief hole to keep it open. I found that nothing , no matter how small, would go through either of my two cylinders. after reading up a bit on this which seems to be a common problem with motorcycle brakes I learned that if that hole is plugged , the pressure behind the piston will not release and the brakes will remain locked or dragging. I think the hole starts out as a 1/8 as drilling that small a hole ( about .011 to .016) would be too difficult unless there was very little metal to go through. If it is too big the consensus was that the pedal travel would increase a bit as the piston wouldn't build pressure until a little later in it's stroke. Just an interesting little tidbit ( I used a very small pin drill to get through the rusted shut hole as just using a wire didn't work)
