engine sprocket noise

[Lance Becker]

I changed the engine sprocket. Went to a 14T instead of the stock 15T. But it's making noise. When rotating the back wheel it sounds like the chain clicks on each tooth. At speed its a wine and fairly loud. When I put the stock sprocket back on, there's do clicking or whine. The sprocket is a SunStar part # 35914. After checking chain adjustment and alignment, many times, I'm riding it and after twenty miles it seems to be getting quieter. Is this normal? Any help will be appreciated. Thanks.