I recently rebuilt the front calipers on a sport bike. 1996 ZX9R. Bike is in new condition. I have rebuilt many brake calipers over the years, master cylinders too, so I am very familiar with hydraulics. But this time I have run into a real stumper.
Replaced front master cylinder with a Nissin Daytona 19 mm radial master cylinder. Replaced hoses with new Galfer lines. Bled system of all air, but was unable to get pressure at the lever.
After bleeding both using the master cylinder and with a Mity Vac, and having the same results over and over, I bled the system using my car bleeder, a KD pressure bleeder. Well, this produced a firm lever, until I removed the system from the top of the reservoir. Again, the lever went all the way to the bar.
I found no leaks. Used 3M Leak Detection Powder to check, had some very slight seepage at a couple of banjo bolts, but those were fixed prior to the last bleed, and I should have had pressure even with that seepage. Seems strange that the lever was firm with the bleeder but without it, it was not.
Any ideas? Thanks in advance for any suggestions.