Check the FSM. There is a round part, which is attached to the bike, through which the cable exits (it's the round part, immediately beneath the choke knob, when it is pushed all the way in). If your choke is too loose, and keeps moving in/out on its own, turn this black 'knob', and it will tighten/loosen the tension on the cable, itself. Perhaps this is too tight? It's simple, and very quick to try. Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII