Front brakes spongy????

Hey all,

I know this is a beat to death topic, but I'm going to lose my shit if I don't get this figured out soon. I've got dual disc brakes on a ZN 750 LTD, and I bled them over and over with no results. The lever doesn't seem to have any pressure in it. I've bled them over and over, many different ways as I found suggestions on this board and others. I've had the M/C apart to make sure nothing was leaking and reuilt it also. Both pistons in the caliper are working fine, and the hose's are in good shape. But it seems that after I start getting some pressure in the lever, it goes away after it sits for a bit. Pumping it helps but it seems like there is still air in the lines. Any ideas on how to get these brake to feel like they are working, I can pull the lever in all the way to the throttle and still push the bike? After a week of bleeding i'm losing it!!! Any help would be appreciated.
Thanks

I usually strap a tie wrap around the throttle grip and brake lever (pulled tight as possible), crack the MC lid and let it sit over night. That does it for me most of the time.

Someone(I'm sure they will)correct me if I am wrong, but bleeding these brakes always seem to be a hassle. Is there any reason that they couldn't be filled with fluid from the bottom up? Use a clean pump oil can or a plastic squeeze bottle? If there are no check valves anywhere, that would push the air out the reservoir.

I have a small rectangle of plastic about 6 x 2 and I flick the lines to shock them. I also sip tie the lever and crack the cap over night. Did you power bleed them. I have never had to but have heard of some that have. GLuck

Did the zip tie trick. Worked like a charm!!! Got brakes now , time to hit the road...
Thanks to all for the info..

Greetings all, I have read many of the ideas posted here regarding this problem. A quick disclaimer, I am not a mechanic, but this is what worked for me. I have a '78 KZ650 and I replaced the plunger and a couple of other parts that I could find for my leaking master cylinder (single, not duel). After I replaced these parts, no pressure. I tried almost everything short of removing the master and slave unit. I ended up purchasing a 60cc syringe; tie rapped the brake lever, filled the reservoir, opened the bleeder valve and began removing all of the air. After two attempts, I had great pressure and was able to bleed the slave unit as normal. This only took about ten minutes (after a week of missing around with the other ways). I hope that this help everyone. I bought the syringe at Wal-Mart in the automotive section; it is used for mixing two cycle oil. Good luck if you run into the situation.