1982 gpz 750 brakes

Well I did put on new galfer brake lines a bit better but the problem still exists. Upon dis-assembly, pistons are piited on the sides but they don't leak. Pistons on Xmas list. I'll see if that has any affect when I install them. I'll update with result. To this point I have tried every method of brake bleeding always the same result, we'll see after new caliper pistons. Brake lever is about 2/3 through before you get any firmness on the lever.

Did you try pumping them and hold?
Steve

That was my thought too. You need pressure pop the bleeder, let lever pull in and keep it there, tighten bleeder, pump again repeat. If you are just pumping with the bleeder open and then closing bleeder without the lever being held it won't work right. That being said if you have a bad line replace it. R

I pump it 5 or 6 times then hold it for 30 seconds, then let it out slowly.
Steve

does 82 GPZ750 have anti dive set up ?

Thanks, everyone for your help, my results have been the same regardless on how i bleed the brakes. I have tried them all. It doesn't have and dive forks, I know Yamaha had those on the XJ series in the same era.

So again, the sponginess could be due to the caliper pistons parking too far away from the discs. You may want to tie back the brake lever again to see if you can get the pistons to creep closer to the discs. I've seen this issue before when K&L caliper seals were used instead of OEM. Pulled some serious hair out over that one.

I couldn't get my KZ1000A2 brakes to bleed after doing a double disc conversion, I had a vacuum bleeder and just kept pulling fluid through to no avail. My problem was solved when I realized, that the splitter on the front was the issue. As the bike was sitting the front was higher than the back where the connection to the MC brake lone is. I unbolted it from the frame and positioned it so it was uphill all the way to the MC. Things improved immediately, but it still took a time to work all the air out by pumping it and eventually tying the lever back. What amazed me was how much difference the tiniest of bubbles seen coming up into the MC reservoir made. I forget the layout of the GPz750R1 splitter I know it's different because, the brake light switch is by the lever, not in the splitter, but check to make sure there is no air trapped there. A bubble the size of a pinhead will seriously effect your braking more than you could ever imagine.

You can bleed at the banjo bolts starting at the bottoms and working to the top. My M/C gave me problems until I took it apart and cleaned everything piece by piece. That was over two years ago.
Steve

Well I'll update on whats happened, after pretty much rebuilding the front brakes, this is what finally worked for me. I "PUMPED" up front brake and held the lever pinned to the handlebar then zipped tied it. I let it set that way for almost 2 days. Removed the zip ties and that finally worked. Tried this before but didnt tie the lever in pumped up mode. Thanks for all the help and tips.