Guys for the last week or so, my walker has been running hot. I have tried everything from air filter, furl filter, spark plugs, changing the oil and filter, to removing the muffler today. I kinda thought that the muffler was the cause, thinking that there is some kind of restriction inside it. It took much longer to get hot with the muffler off, but it still set the bells and idiot lights off when I was mowing. I'm gonna replace the muffler with a new one, but it wasn't the cause of the engine getting hot. I'm out of ideas other than just the motor being wore out. It has 1400 hrs. on it right now. It runs, starts and mows perfect just gets really hot after running about an hour.