Sounds like an internal part of the governor broke. I don't know squat about Kawasaki engines, so can't be of much help.

I bought an aftermarket igniter and the mower runs great now !! The new one from ((http://www.rcpw.com/aftermarket/440465.asp )) cost $20.00 & works fine !! (NOTE , I did buy the John Deere one for $63.00 & it lasted exactly 20 minutes before expiring ) I mounted the new one by the run relay under the seat , by the battery (it comes with the necessary wiring) !! That John Deere has turned to junk aftermarket parts is sad , but true !! Wonder why they don't go for the aftermarket parts that are actually good and work ?? If anyone needs info , I did break down and buy the shop manual for this unit & will be glad to email the section to anyone with problems with sx , rx 70 or 90 series issues !! thanks , jeff Here is a link that might be useful: Kaw Igniter

tps, you can test for a "vacuum leak" by running the engine at low curb idle and spraying a very small burst of carb cleaner (use the straw) on the intake manifold gasket flange or other suspicious part. If a vacuum leak is present, you will observe a slight, momentary increase in the RPM. Don't "over-do it" when using this technique. First of all, if you spray too much of the combustible liquid, you could catch the fluid on fire if it finds a spark, just spray a little bit and let it dissipate before spraying another little burst. Secondly, if you spray too much, and the engine picks up this "additional fuel" through the air filter, you could get a "false positive" increase of RPM. Of course the engine will smooth out at high RPM when you apply the choke. When you apply the choke, you are strangling the engine by reducing the size of the induction system (much the same as if you swapped the OEM carb for a tiny carb). The OEM carb is sized with the intent of allowing this engine to get enough fuel and air to do some heavy, hard work. Shucks, just sitting there running at high curb idle ain't no sweat.

My Engine is a Kohler single cylinder Model CV490S. Tractor was purchased new in 2003. I drained the oil before I removed the cylinder head. I have now located a manual for the engine, but the trouble shooting area of the manual did not provide any help. Plan to put a fuel shut off valve before the filter also to make sure that fuel does not leak into cylinder again.