6th Gen: Need help bleeding the secondary master cylinder

Hello Folks, i need help as i've bleed two times the rear brakes until no more air comes out...

there seems to be a problem or just air between the pedal to secondary master cylinder or secodary master to rear brake claiper..

when i first got the bike it has a piece of pvc hose connector and a hose clamp preventing the secondary master cylinder from moving, front brakes never had a problem with them, before removing this "MOD" rear brakes would work, never lose pressure but i noticed that no matter how hard i pushed on the pedal i would not get the rear wheel to lock up (non abs model). when i removed the so called "mod to unlink the brakes", that now im starting to believe it is there because there may be something wrong with one of the parts... when i removed it the brake pedal went to the bottom as soon as the secondary master cylinder started to move.

Since i just got the bike a couple of hundred miles ago, maybe more, 4 months, i decided to completely flush the system for both brakes and install new pads as i only had about 1 or 2 milimeters of pad material. using a vacuum pump i drained all the fluid from all bleeding valves.

Intalled new pads and bleed following the manual, front brakes were no problem, for the rear, from pedal to rear caliper was ok but i could not locate the RIGHT SIDE (oposite to the battery) proportional valve bleeding valve, some said its only for the ABS model, well i just skiped it. then using my vacuum pump bleed the pedal to front caliper (center valve) then the left side proportional valve and finally the rear caliper center valve.

brake pedal would feel hard until the secondary master was moved, then the pedal gets soft and goes to the bottom.

i tried using the method posted on the ultimate guide on this forum, using a helper, pumped the pedal to fill the secondary master, then just one push on the secondary master while opening the proportional valve, then while holding the secondary master pressed with the proportional valve closed, i had my helper pump the pedal until the secondary was all the way out, and then opened the proportional valve and pushed the secondary master again and did this lots of time even that no air was coming out just to make sure, i did this two times, brakes would work ok, but i was losing pressure on the rear brake pedal continuously while riding if i using the front brakes (causing the secondary master to move) i had to pump the pedal to get it hard again but it would get less pressure from time to time until no pressure could be archived.

i need some tips as i am getting bored of removing the rear wheel and caliper to get access to the bleeding valves.

 

Hello again, i went out and i spent two ours bleeding and bleeding, tried the method here, pumping pedal then the secondary master cylinder (one time) until no air came out, then just to make sure, as i always do, turned on my vacuum pump, there was fluid coming out, but here comes the strange part, the level on the reseirvour never went down, somehow after pumping for some time (one minute) seems like i was getting all the fluid out from the lines and then air was being sucked into the lines, first i thought i still had air in the lines but i did this too many times, about one quarter of fluid and could not stop getting air when using the vacuum pump as recommended on the honda manual with he caliper tilted and so....,

i dont seem to have any leaks that i can spot i just found that the secondary master cylinder was a little bit wet under the rubber boot.

could this be my problem??, after two hours of seeing too much air coming out from the lines when using the vacuum pump i ended up bleeding as before and installing back the hose clamp to prevent the secondary master cylinder from moving.

i got one more question... while bleeding with a vacuum pump connected to the servo proportional valve (battery side), shouldn't the fluid level on the reseirvour drop whie the fluid is being sucked out?, as i said, i believe air was getting into the system from outsite and i believe the secondary master cylinder is the culprit...