A number of you requested more information on the o-rings used to quiet down the clutch rattle on various 2005 Yamaha RS (three-cylinder) 4-strokes. The noise will not cause any mechanical problems, and is said to be a result of the power stroke interval characteristics of the three-cylinder engine design. The noise comes from the clearance between the primary clutch sliders and the moveable sheave, with the fix being installation of a new style slider button with an o-ring on the driver side of the spider.
Not all 2005 RS models experienced this. To install the o-ring and new slider, the primary clutch must be removed and disassembled to allow access to the sliders. This requires special tools, so if your sled exhibits this condition consult with your Yamaha dealer for the appropriate repair to be performed.