My bike was idling a little rough and there's always noise coming from the transmission crank case. It doesn't affect the riding. Just very annoying when bike is idling. First I ordered a new transmission belt. After taking out the old belt, I realized that the old one and new one have different part number. Since I'm not the original owner, I'm not sure if it was original or replace incorrectly by previous owner. After the new belt, the bike idle much smoother. But during installation, I accidentally damage the pulley weight and probably something else. So I decide to replace all the CVT transmission including the pulley assembly and clutch assembly. Just got my parts last night and installed them. What a difference. Bike is in like new condition now. I always thought it was a clog up carburetor causing the idle issue. I'm just glad that everything is good now. My bike is a 2007 with 12,000 miles.