I have had these problems with kohler motors also. The reason is the piston clearance is a few thousands less than most of the older mowers. Fact: Make sure that you idle your mower down all the way before you shut it off. If you don't there is a chance that you could over torque your rod and have to have a rebuild job that could happen everytime you shut your mower off. These high compresion motors really need to be idled down. It will save your motor
You should let every piece of equipment idle for a few minutes before shutting them off. It's kinda like when a human runs a mile they say it's good to walk for 10 minutes afterwards to let your body cool down. Hope this will fix your problem.
I read in the Kohler manual that for engines that are not equipped with a shutdown solenoid, you have to let them idle before you shutdown to avoid the backfire problem. <p>Some engines have them, some don't.<br><p>----------<br>D. Tom<br>
The reason the engines backfire is this. In order to help the engines to keep from running lean and burning pistons or valves, they run a little rich in the fuel mixture. When you let them idle, this extra gas builds up in the muffler and when you shut the engine off, there is actually a heat soak for about 20 seconds. This means that the muffler gets hotter after you shut the engine off, than when it was running. It gets hot enough to autoignite the fuel mixture, thus causing a backfire. I believe the exmark manual recommends shutting them off from half throttle to alleviate this problem. This richens the mixture in the muffler enough that there is not enough oxygen in the mixture to autoignite. No backfire. The backfire should not cause any problems inside the engine, since this all happens in the muffler.<p>hope this can clear some confusion up<br>
I had the same problem wit my 25-Kohler.The distributor advised me to shut it down at half throttle. It works.I had a 14-Kohler that blew up three mufflers. The third one cost 140.00 with the (special mounting kit.) They were under warranty. <p>----------<br>Bobby <br>Ft Lauderdale<br>