Nope, nothing.
The engine does make a 'chirp' noise if i rev it, the squeal seems to be an extended version of this.

Got a little video if it helps at all, will try to get one of the bike pulling away although it would be tricky to film haha.

The chirping sound can be heard 17 seconds onward in the video.

https://www.youtube.com/watch?v=jsknYyJ7j3k

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