I have a Kubota Z421kwt with a Kawasaki Fs730v engine that has about 100 hrs on it. It was surging at high idle. I’m currently recovering from a broken ankle and my wife was going to mow the lawn for me. A friend of ours looked at it for me. He said that he adjusted the idle speed screw and the surging went away. I don’t believe that screw should of been messed with. I would like to put it back to factory position. Does anybody know how many turns out the screw should be. I haven’t tried to start it since. I don’t want to cause any damage.
check the top of the carburetor for any missing plugs. Most of "that" issue plagued the early FX series Kawasaki's but I have also seen a couple FR/FS series with a missing welch plug, causes surging (lean running).
If that's ok, there are 3 likely causes in the order of commonality from most to least. (1) junk inside the carb, causes restriction, lean running and surging. (2) loose carburetor or intake manifold causes vacuum leak. (3) plugged engine cooling fins. Nowhere for the cooling air to go but to the air filter, which kinda supercharges the engine--and it surges.
