Here is another Honda technical item that few outside of factory trained and dealer experienced mechanics are aware of.

Ever notice the rubber sleeves attached to the outside of the springs on Honda motorcycles? They're on the carburetors' throttle return spring, and even on the springs that are part of the cam chain tensioners. Wonder what they are for? They damp sound.

Part of being a vehicle manufacturer means having to submit to regulations governing vehicle noise. A ride-by test using a decibal meter is (or was) actually used by the Feds on every vehicle sold in the US. The intake systems are quieted by Honda by restricting them, and among other things, even some rattles and harmonics are controlled, including that of the springs. By the fitment of the rubber sleeves. There is even a rubber washer on the drum type rear brake panel that is designed to reduce squeal.