Fluid Not Coming Out of Front Brake M/C

My husband has a 1976 Kawasaki KZ900 Z1 and he just got a front brake master cylinder for it. The problem: brake fluid is not coming out of the master cylinder. He still has it off the bike and using the lever, he pulls it and nothing comes out the hole where the lines connect to. What could be causing this? He has used the air compressor to make sure there aren't foreign particles inside, he can see the plunger moving back and forth thru the little hole inside the cylinder while looking down into the cylinder, air will go thru but the fluid won't. Any help would be appreciated since he has had the bike for years and has rebuilt it from boxes of parts. We want to ride this year!! Thanx

Most likely your master cylinder has air trapped inside. I like to attach one end of the brake hose to the master cylinder and submerge the other end inside the master cylinder reservoir 3/4 full of brake fluid. Slowly pull the brake lever and watch the air bubbles come up from bottom. When there are no more bubbles, you are now ready to attach the bottom end of the brake hose and bleed the air at the front caliper bleeder screw.

Would download the factory service manual available in KZr's FILEBASE, and begin at page 103.

Z1-KZ900 FSM

Am guessing the relief port or supply port might be obstructed.

Good Fortune!

So basically, the brake fluid won't come out as long as the line is filled with air? So like once I get most of the air out, it should start working? I'll have to try that.....thanx GPz550D1 I'll get back to you..........