Because there is a design flaw in the Kawasaki water cooled engine.
front hud
Try www.bikebandit.com, they have a large selection of oem and aftermarket spark plugs, if you keep fouling plugs try to rejet the carb, or swith to a hotter spark plug.
Oil and gas mixture too rich. : o )
According to the Gator manual the gap is 0.8mm or 0.032 in.
John Deere makes good lawn mower replacement parts. I would probably go with John Deere or Honda spark plugs, if I had to make a decision on what brand to get.
The 8.1 is a diesel motor, no spark plugs.
Correct tuning, correct heat range plug, correct oil/gas ratio for the motor
Valve guides are worn and piston rings are worn crank case oil seeping up to spark plug fouling them change spark plugs or try irridum plugs they sometimes work in engines that consume oil.
it could be piston rings letting oil get on them it happened to mine
This sled was meant to run hard and fast you probably are fouling out your spark plugs.
Bad fuel mixture, jets, carb adjustment. try to keep engine reved high
the engine will run "rich" fouling spark plugs and causing bad fuel economy.