PeteK, He did. (I think he did.)I took the old sprocket and placed it over the new one and began to spin one of them and match up the nut holes to see if the teeth match up and they only match up perfectly in 1 specific spot.
The KLR front sprockets are stepped on both sides. The THINNEST step faces the Engine. This places the front & rear sprockets into direct line. And helps keep the chain master link from touching the LH Lower sub-frame bolt (Which some people intstall TOO Long of bolt into, and it then causes tick, tick, tick with rider on board).
Next up, the drive chain needs to be LOOSE Enough to lift the lower run up with 1 finger to just touch the rear tip of the rubber underslider of the swing arm. Otherwise when the suspension compresses the chain pulls 'bow-string' tight.
Next, you may be simply hearing the 'ssshhhhhhh' of the very tacky assembly grease on the teeth of the new front sprocket. What brand of sprockets did you purchase? Some are more smoothly manufactured than others.