06-17-2013, 01:00 PM
(05-26-2013, 11:14 PM)ridesalot_imp Wrote: jodyz, a few general thoughts on the noise you are hearing. If the noise is coming from the inside of the motor, rattling sounds can be produced by a malfunctioning cam chain and its tensioner. It will be interesting to hear what the mechanics discover.
If the source of the noise is outside the motor it should be easier for you to find it by checking for tightness on all nuts and bolts which attach to either the motor or the frame.
A normal sound which you can hear is produced by the AIS (air injection system). During idle and low engine speed the AIS introduces air into the exhaust stream acting like an afterburner to burn any unburned fuel that reaches the header. This is accomplished using valves which are opened and closed by the CPU. The resulting clacking noise is audible. The AIS can also produce a popping noise on trailing throttle.
I believe that at idle and low rpm I can hear the cam doing its job. I would have to think of this as normal noise as well.
It's definitely an unnatural engine sound. I need to find a place to post my sound clip.