was out fishing last sunday off the cape and motor was running fine like it always has then in the after noon after fishing a location started the motor up and a soon as I hit 3,500 rpm or so she made the wrapping sound inside the egine block oil was fine gas good new powerpack last year new plugs so I preety sure I have a blown cylinder or almost sure off that I idle down a she ran with the knocking the rest of the weigh in .