So this has been present for a long time and I would like to get to the bottom of it. It sounds like a playing card being brushed on the spokes of a bicycle wheel. Video below. It happens when:
1. I press the throttle at a certain point, which can vary by gear, road, etc, but it almost always does it at some point.
At first I thought it was something vibrating at certain frequencies, but the noise occasionally happens right when...
2. I press the engine start button for a split second as the starter does its thing before the engine even starts up. This is less common but has ruled out a sound due to frequency.
Also, it doesn't happen when using SRM downshifting, which also helps disprove vibration and sound frequency as causes.
What mechanisms are common in our throttle and starter/ignition processes (but not synchro rev match) that could cause this?
Any help much appreciated.
https://youtu.be/TkYJz3yaNP0
EDIT: Replaced with YouTube link.