Question about high rpms on Honda 1981 CB750

Hey guys, so when I apply constant throttle the bike seems to jump to insane rpms while in neutral. So for example, if roll on the throttle at 20% and keep it at 20%, I can hear the bike go from like 3000 rpm to 6000 within a second.Some possible reasons that I can think for this would be that the idle needs adjustment? I am also missing a push cable on the throttle but I heard these don’t really do anything other than act as a failsafe. I recently cleaned my carbs and the seals for the hoods didn’t seem like the best. So I’m thinking it could be an air leak? I’m really not too sure so any help would be great. Thanks guys! via /r/motorcycles https://www.reddit.com/r/motorcycles/comments/d17x07/question_about_high_rpms_on_honda_1981_cb750/?utm_source=ifttt