1981 evirude 90 only gettingto 4000 rpm

[jrivera7294]

Hello Everyone. Hopefully someone can help me with my problem. I just purchased my first boat which is a 1981 mako17 with a 1981 evinrude 90hp. the Motor idles a bit fast at about 1000RPM. I want to know if there is a way to adjust my throttle. When I throttle down all the way the boat motor is only getting to about 4000rpm. I have taken the cowling cover off while running and manually opened the throttle which quickly launches the boat to a plain and gets the boat up to about 5200 rpm's. How would I adjust the throttle so that i can achieve this kind of throttle response from the stick.