I replaced the 16 tooth front sprocket on my 1981 SR500 with a 17 tooth one, bad idea. I kept hearing an annoying intermittent squealing sound at highway speed. Turns out the bigger sprocket let the chain rub on the transmission casing at times. By the time I figured out what it was, it had cut a nice little grove in the casing. Not enough to go through though. I ground just a little more off the casing so it wouldn´t rub anymore. Took care of the squealing.