Front brakes locked

[Harrpics]

Hi all,  Hoping for answers! Have rebuilt front calipers and master cylinder on 94 K1100 w/o ABS. New brake lines, too. With reservoir cover removed, I bled the brakes and have a good lever feel. On the bench, the wheel spins freely and the brakes work properly. When I put the bellows and cover on the reservoir and apply the brake, the pistons will not release and the wheel, obviously, is difficult to spin. Thoughts? I've read there's a vent hole but also read there is no vent. Really puzzled. Thanks! 

[Laitch]

I've read there's a vent hole but also read there is no vent. 

There are two holes in the floor of a Brick's front master cylinder reservoir, regardless of what you have read. One of the holes is much smaller than the other. Empty fluid completely from the reservoir, wipe the reservoir with a clean, lint-free cloth and observe. The smallest could be clogged; a fine wire will be needed to clean it. Attached is a photo of a 2V front master cylinder reservoir showing the difference in diameters. Your 4V master cylinder will have a similar difference.

[Harrpics]

Thank you so much. Will empty the reservoir and take a look tonight.