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59096 1989 GPX250 in your profile, if thats the carbset you are working on, WOW 30 years old...... at that age...its imperative to renew ALL the seals while apart...the tiny pilot screw orings, bowl orings, the actual float valves, and both *rail and *vent orings.
*these require "splitting" the rack to accomplish and may have never been done.