Front Brake Master Cylinder recommendations

Hi all, I changed the handle bars on my 1990 KZ1000P so I could get away from the big ape hanger style. When I did so I wanted to change the M/C to the straight one. So I go to ebay where they have M/C that will fit KZ1000's. Well, first one was not large enough (not 5/8") so it was spongy. Second was advertised as 5/8" but is also spongy. I am looking for a recommendation of what I should use. Any help will be appreciated. Thanks, Keith

did you check the tiny return hole in the reservoir? My brakes were pretty soft after i cleaned them, realized there was a tiny bit of debris in there. just pushed a pin in there to get it out and was able to get a firm handle.

I did notice some bubbles coming from that hole. I will inspect it to see if there is blockage. Hopefully I can use one of my new M/C's. I was looking for alternatives that may be available if I must give up on these. Since the bike is a police model and the factory equipment would be tailored to the apehangers I realize I have to go back to a version that uses a smaller set of bars, if that makes sense. Well, I'll cross my fingers and hope the good doctor is right. Thanks doc, Keith