Why does my Fazer sound like a sewing machine having a fight when its idling?

[JZS 600]

Just did a round trip of 80 miles round the M25 this morning in -2  :eek  to Fins at Redhil to get a new clutch fitted (under warranty, good service Fins) on my Foxeye Fazer.
First Fazer so not sure what to expect from the engine but will get the carbs balanced anyway.
Bike rides really well so happy with it.    Good stuff.