help needed with whining noise!!!!

[Yamazer-92]

Since changing my chain for a heavy duty x ring my bike makes a whine from the sprocket / left side of engine sometimes too usually in 6th gear at around 50-60mph. I thought it might be because I didn't put a gasket back in when I replaced it and it could be vibration of the front sprocket cover and engine, but I have left it because it sounds cool like a supercharger and to my knowledge is doing no harm    (Done 2k miles on chain, still looks like new as does the front sprocket and nut).