YES I HAVE A TORO PRO LINE 118 WITH A 18 HP MAG. MOTOR MOWER QUIT RUNNING WENT TO START IT BACK UP AND IT WANTED TO START BUT IT SRARTED BACKFIRING TOOK THE PLUGS OUT ,GOT FIRE WENT TO SEE IF I HAD ANY COMPRESSION AND NOTICED VALVE WAS NOT CLOSING WHEN I TURNED THE MOTOR OVER ,MOTOR TURNED...