I have a 52" exmark with a 23 Kaw. It has 144 hrs on it and is about 9 mos old. About 3 mos ago it started losing power. My dealer said it has been pretty dusty around here and said the filter was dirty which caused the motor to run too rich and caused the spark plugs to get heavy black deposits on them. They said that Kawasaki's need to have very clean filters or this will happen. They said to change the pre filters each day. This has not worked. I can put a clean prefilter and clean off the plugs and by the end of the day you can tell there is a loss of power. I feel like my dealer is giving me the run around. Its not that dusty around here, we've had plenty of rain. I noticed some oily residue below the air filter inside the carburator. I cant believe that all this headache is due to a filter that looks almost new. It seems to me the carb is running too rich, but the dealer says it doesnt have the same adjustments on it that other carbs have on them. I would like a second opinion from another dealer.