No cylinder pressure, front disk brake on Honda CB450SC

[Brasidas]

I rebuilt the front brake caliper of my 82 Nighthawk, taking the cylinders out, removing the old seals, cleaning everything, putting in new seals, and changing the brake pads.

I hooked up my caliper, pulled the brake handle, and I've got no pressure happening on the pads and presumably the brake cylinders.

I'm attempting to isolate the cause and address it. Help would be appreciated.

First guess was the seals on the cylinders. There's no fluid coming out there, so it seems to be a good seal.

Next guess was an airlock in the brake line. Put a fluid-filled tube on the bleed valve, and oriented the tube upwards. Cycled through opening the valve and pulling the brake handle. Air bubbles came up the tube for a few cycles then stopped cold.

When I pull the handle while the bleed valve is open, the fluid level in the tube moves, which seems to indicate that there isn't an airlock in the master cylinder itself.

How do I go about troubleshooting this sucker to confirm where the problem is and how to address it?

[Wrider]

I know it sounds stupid, but are the cylinders in the right way? Empty side of the bucket out? If not then I'd suggest using a mity-vac to reverse-feed the fluid, pressurize it.

[pchast]

I see its been more than a week. hope its already fixed but here:

I had the same before when I put the seals in the wrong way. The cups need to flare to the wheel side in order to produce pressure. If wrong way round you will still see the fluid move in that tube but have no pressure in a closed system.

Of course you could have a different problem..... triple check that you bleed all air out of the system after checking that all cups are right.