Okay, I bought a 2007 TW200 today. It came with a 44-tooth sprocket installed. The original stock 50 tooth sprocket came with it. I took it all apart, and put the 50 tooth on. Then I realized that the chain was to short. So, until I can get more links I put the 44 tooth back on. Now, when I drive, it makes a rattling/rubbing noise. I think it is from the chain guard rubbing the tire, but I took it off and put it back on again double checking my work. It made the same noise.