A week ago when I started my 01 F4i it sounded like it blew a spark plug making it sound like a damn lawn mower. I ripped apart the bike put new ones in, fired it up and it still sounds the same. Could it be that one of the coils is faulty causing this? Should I gamble and just replace all of the coils just to be on the safe side?

 

well test each plug and see if theyre all getting spark. If they are i dont see any sense in replacing the coils. Try and find out what the problem is before you go wasting time and money replacing unnecessary parts. Run the engine for 5-10 minutes and spray some water on each header, see if any of them are still cold and youve dropped a cylinder. If everythings fine and it just sounds loud/like a lawnmower you could just have an exhaust leak and you may just need a new gasket somewhere. More details would be helpful.