Trouble bleeding front brakes

Hey all - long time no post.

So I am back to work on my z and am having a tough time buliding up pressure for my front brakes.

The specifics:

New master cylinder, aftermarket from that guy selling them on eBay.

New stainless steel brake lines

Rebuilt calipers

Dual front disk setup

I used a vacuume pump to bleed and also tried the good ole' lever pump, hold, crack bleeder, (spurt - no air), tighten bleeder. I went through an entire can of brake fluid and still I can pull the level back to the grip when I grasp it hard.

The brake engages when I spin the front wheek, but it feels too mushy.

The bike isn't on the road at the moment (no gas tank) so I can't ride it to tell if that is just how it feels and it is working, or not. So my question is, could this be a normal feel for the dual disk with steel lines and a new (but semi-cheaply manufactured) master cylinder? Sound like I am missing anything?
:dry:

No, you should have a very firm brake with your new components. You have some air bubbles somewhere. I had to remove the calipers, and raise them above the level of the M/C, then bleed them again to get the last bits of air out. Also, after I got it close, I used them for about a week, then did it again. My handle is extremely firm now.

If you search, you will find a number of old threads that discuss this same issue. Good luck, and let us know what finally works for you.
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Sounds like what I will be trying next then. Thanks for the advice apeman.
I will no doubt let you know how it turns out.

D@mn .. your name got that Kinks song stuck in my head now. :laugh:

pull your lever back as far as it will go and zip tie it to handle bar leave it like that overnight,then come back next day and crack bleeder valve open.that should force the air one way or the other out of system then bleed the other caliper normally;)

Just ran out in the garage and zip tied it right now! Thank u sir.

SIR ?????? im a semi retired plummen,electrical,hvac contractor.i work for a living (sometimes anyway!!!:laugh: )

WhenI did my brakes it took a good two weeks before they firmed up to where it felt good. I would take off the cover and pump the brakes slow and watch all the little tiny bubbles come up. That went on for about a week straight then it felt good enough to ride with.

When you put a new or rebuilt master on a car or bike you really should "bench" bleed the master first. I have a kit with fittings that pumps the fluid out and back into the resivour. Trying to pump fluid through a dry system with something that is not even bleed itself is a nightmare. That's what these guys are basically trying to tell you, the air is most likely in the master. Sometimes you can have trapped air in the calipers also which may require you to remove and rotate to have bleeder pointing up. Careful with the "lever pumping then crack the bleeder way", pump it too hard and you can take one air bubble and turn it into 20 bubbles. If your still having a problem you can also crack the bleeder first and then slowely squeeze the lever. Let us know...

Just remember that you will probably have to hang the calipers at a certain angle to get all the air out.I went through the same thing,and eventually,that's what I did and it worked.Experiment with different angles and you'll get it eventually.
Don't forget to insert a piece of plywood in between each set of pads,so the piston doesn't push out all the way(and the pads.Make sure the plywood is thicker than the rotor.
This will make it much easier to re-install the calipers back over the rotors.

Consistent with the above good advice about correctly positioning the caliper when bleeding the brake lines, the FSM Supplement for 1976 KZ900-B1 LTD has instructions for bleeding the front brake lines which specifically include removing the calipers and holding them in position whereby the air bleed valve is on top pointing straight up during the bleeding operation.

Uncertain about exactly which caliper design is involved here or how the bleed valve is oriented with caliper mounted in its usual position on the bike.

Good Luck!

I bought a pair of speed bleeders and they did seem to help with bleeding the lines. I will have to get them back on and rebleed sometime next week though. You might give them a try, I got them off eblay for about 7.00 each.

Just one small thing to add to all the good advice already here, if you take a screwdriver handle and give the master cylinder and calipers a sharp rap. This will loosen any bubbles up and let them go to the bleeder.