Brake calipers

[Ridgeback46]

Golwingers I need a little help!
Last fall I bled the rear brake system and yes I know the front is linked. On 2 separate occasions I have bled the system and achieved a pedal that moves the amount that people on this site say is all one gets. Then I put the bike away for the winter and when I go to ride the pedal is flat again, I guess that air has penetrated the system.
A few years ago I replaced the complete master cylinder but it still appears that air is getting into the system without any sign of a leak.
Any suggestions?
Now I think I should replace both the calipers and get done with it!
Where would be a good place to buy calipers? Keep in mind that I am a Canadian!

[MikeB]

Pump up the brakes with the brake pedal until you have a high pedal. Place a heavy weight on the pedal to keep it depressed for several hours, overnight is good.
I've heard that this should work the air bubble up and out of the lines.
Then bleed the brakes again as specified in the service manual.

[Ridgeback46]

Thank will give it a try!

[Rambozo]

At the end of the winter when you take out the bike, is the fluid lower or higher than when you put it away?

[Ridgeback46]

Not so as you would notice! The reservoir is still close to the top.

[thebruce]

A mityvac (spellcheck tried to change that to mitzvah) may also help pull the bubble through the system faster than it can rise through the fluid.

It helps to have a helper and a goodly amount of dot 4 around if you are bleeding the brakes by attrition like this.

Mazel tov!