The Kawasaki FC290V engine in my John Deer RX75 mower hunts when running with no load. I suspect that the carb has some sort of blockage, either in a fuel jet or an air passage. I can run the low speed adjustment screw in and out and nothing changes. I also did a static governor check and that seems to be adjusted properly. I downloaded the service manual from mymowerparts.com/pdf, but page 15, the page covering low speed adjustment and choke adjustment, was blank! Any one know of another website that I can try to download the page that I need? Page 18 said to check the diaphragm for holes or cracks. The exploded parts diagram doesn't show any diaphragm, and I can't find one on this carb anywhere! Any ideas? As it is now I can operate the mower since the "hunting" pretty much goes away when under a load at full throttle, but it is very annoying, and it won't idle at all, it just quits if you bring the throttle all the way back.
Thanks in advance for any help anyone can suggest.

The most common reason for this issue is a plugged or restricted pilot jet in the carburetor. Look at a parts breakdown for your carburetor and locate the pilot jet, then take the one out of your carburetor and clean it out good, clean the passage ways in the carburetor that supply the pilot jet as well. Reinstall and all should be good.

Best of Luck....

Thanks for your suggestion. I already tried to remove the pilot jet. In the exploded diagram it appears that it is threaded, and should unscrew. However, after removing the cover plate, the jet seems to be loose in the hole, and just spins around when you apply a screwdriver to it. But it doesn't seem to want to just fall out, and resists removal with needle nose pliers. Are the threads somehow stripped? To my knowledge the carb has never been dissassembled, so I don't know how that could have happened. Anyway, I agree that the problem is probably in the pilot jet since adjusting the low idle screw has no effect on how the engine runs, and since it won't idle at all. Just don't know how to remove the pilot jet! Any other suggestions that don't involve the employment of tactical nuclear weapons would be appreciated!

As usual, 30year was 100% on target. The pilot jet was being held in by it's "O" ring. A gentle tug using small needle nose pliers and it came out easily. It has a slot on top, but it's not for unscewing, it's used to orient the jet properly when installed. Anyway, the pilot jet did indeed have the slightest bit of "junk' plugging up the small hole on the bottom. Also cleaned the rest of the carb up while I had it apart. Upon reassembly and start up, it runs great and idles smoothly. Still looking for the missing page from the service manual............ anyone know of another source for downloading lawnmower engine manuals?

I was just fixing to post, that I thought the pilot jet on your carburetor may be held in place with an O-Ring, but you beat me to it. Anywho, glad that is all working good for you. I had a link to a site with service manuals, but I can't seem to locate it. If I run across it again, I will let you know.