Mazda B2200 1989 Replaced Mastercylinder But Still Brakes ,

If you have replaced the mastercylinder with a new one and bled the brakes several times you can most likely cross those off your diagnosis list. If however the master cylinder was used, it could have been just as bad as the old one. Check the brake lines from the master cylinder to the brakes and make sure there is no sign of rust or leaks. If you do find there to be a problem it is best to replace the brake lines. Make sure the brake fluid reservoir above the master cylinder is to the full line. When was the last time you changed the brake shoes or pads? The braking problem could be form warn out brake pads on the front or shoes on the back (if applicable). If the brakes are hard when you try applying them it could be a problem with the brake booster. If all of this checks out though,  it is best to take it to a mechanic who can diagnose the problem more accurately. 

I hope you get this problem resolved and it is nothing major. Have a great day!