Had the exact same problem. Warped rotors. Fixed.

 

UPDATE EVERYONE: so it turns out it was 110% the ROTORS. I put the new ones on, bled a bit, took the bike of the jack (expecting the worse) and all of a sudden I finally had brake pressure. Took it for a ride around the block and it felt great. Went riding all morning today. Thanks for the help everyone

 

I am glad you are back on the road.I hope some that totally disputed that it couldn't couldn't be the rotors learned something.Again it is great you are riding again.Thanks for the update.

 

They had to be really, really bent - and not just warped.
Plenty of people on here daily with a "bent rotor" post that don't have a loss of hydraulic pressure. Same with cars.

On a normally functioning dual piston caliper system, a warped rotor will cause the caliper pistons to rock back and forth (in and out) inside the caliper and cause the lever to pulse.

I'm wondering if his problem is really solved though.
Stated that he had to rebuild the calipers due to frozen pistons...
What rebuild kit did he use for the brembos?

Anyway, glad it's working out and he's back on the road.

 

geezer glide 56...I learned something today. U R DA MAN

 

OK OP, it seems that since you have left it sit, the air in the lines bleed back into the master cyl., that is good.
Just curious, did you bleed the master cyl BEFORE bleeding the calipers? If not, you will continue to get air.
Just a thought!!
Roger

 

If the rotor is warped enough The piston will be pushed back into the caliper bore and will not return to it's operating position until the lever is pumped.If the rotor has high spots on it or a very slight warp they will do as you say,you will in fact feel a pulse in the lever and not lose lever pressure.Usually rotors get bent when someone is careless changing a tire or wheel,or installing a wheel that is not properly spaced between the forks.

 

Totally agree with you. The other thing I was thinking was those frozen pistons.
On a single caliper with dual pistons, if only one piston is frozen, wouldn't take too long to straight up bend/warp a rotor up with only one side pushing.
And the frozen side... yeah probably causing a lot of heat if it was stuck in the out position.

Hope the OP has those calipers dialed in now...

 

I used just a regular rebuild kit fr jp cycles. I don't have brembos on my bike. The last few rides I took there was a pulsing when braking hard, probably due to the rotors warping. Like I said before there was always a brake drag when I bought it, the piston probably froze on the last few rides and caused it to over heat everything

 

But thanks everyone I'm thrilled I'm back riding