Any of you guys having problems with you kaw motors. Ive got a exmark 52" with 23 Kaw. Its been running kind of bad, blowing some black smoke and sputtering. Gas is clean and no water in the fuel. My dealer says the air filter is dirty causing the motor to run rich which blackens up the spark plugs. I keep great maintenance on my mowers especially filters. I put a new filter and plugs in today, runs like new. My dealer says as dry as its been down here I need to change prefilters every 3 or 4 days because the Kaw is a high performance engine and is more sensitive. He said he's seen several in with the same problem. The filter I changed today looked pretty good. Ive seen alot of threads on problems with Kohlers. Ive had 3 mowers with Kohlers and never had a problem like this, theyre not this temperamental.