That could be a number of things really. What is the bikes mileage? Is it smoking at all? Is it still firing on both cylinders? Can you tell which area of the engine the knock is coming from? Front/back cylinder and top or bottom of engine?
My initial instinct suspects your big end bearings could be shot but could do with a bit more information. How much power has it lost? 50%/60%? etc Click here
My initial instinct suspects your big end bearings could be shot but could do with a bit more information. How much power has it lost? 50%/60%? etc Click here