I have a 23hp kawasaki on a walkbehind mower. Ever since new it hasn't been quit right. Close but not quite. It would foul plugs quickly. NOT run smoothly at anything less than full throttle. Idle would surge up and down unless under load. My dealer has been great trying to fix this and make it right. It seamed that the vent to the float of the carb was causing it to run rich and uneven. First he moved the vent hose away from the engine and below the engine deck to get away from the air flow coming off of the engine. This helped but it didn't last and wasn't enough. The problem came back. He cleaned the carb a couple of times with limited results. We moved the vent hose again to outside the engine deck by the wheels to get away from the air off of the hydro cooling fans. Again this helped but not 100%. Finally Kawasaki admitted to him that their was a problem with some of their carbs. Last weekend he replaced the carb again only this time with a new style of internally vented carb. WOW now it sounds like a different machine. The engine runs noticeably smoother than before in all conditions. I didn't think it was too bad lately but now I know how it is supposed to be. Smoother running quieter, and more power. The moral of the story is for anyone having problems with a recent Kawasaki v-twin. Check your carb or have the dealer do it. The new internally vented carb is the way to go. These newer engines area running so lean that any variable like a simple vent having air blow near it can really mess with the mix.