bad throttle response

bike starts up and idles good... when i twist the throttle, rpms go up and stay up there after i let go... points?

Vaccum leak. Carb holders are cracked or loose or a vaccum port could be unplugged.

Check to make sure that your throttle cables are adjusted properly. Also the return spring on the carbs
may be weak, not allowing the throttle to return. Try disconnecting the cables and operate the butterflys by hand to see if the problem goes away. I noticed on my KZ550 that if the cables don't have the proper adjustment in them the engine will do all kind of weird things.

The throttle cable tip is a good one... it is unlikely a return spring issue on the BS34 carbs as there are three separate return springs and never saw these go "bad" or loose tension. The tip on air leaks is also a good one. On older sets of BS34s I would also add that the orings on the mixture screws harden and tend to leak air and should be replaced. The other places suggested for checking are correct... just adding one more.