rear brakes loose pressure

[1chado]

hey guys help!!
I have a 2001 honda 350ex the rear brakes don't hold pressure. I replaced the pads, had the caliper checked, and replaced the master cylinder. When i tested it after bleeding the brakes it worked awsome, but then after a little bit the brakes go back to nothing and i have to pump them to get pressure back but only momentary. What am i missing.
thank you
new guy

[Natertot426ex]

First of all welcome to the site. Have you checked your Brake line for leaks? That seems to be the only thing left. Someone may have a better idea though.:D

[Raptor555]

Check your rotor and make sure it's not bent.

[Bean]

maybe blown o-rings around the pad pushin clyinders, loose or cracked brake lines also