Engine sounds rougher when accelerating from 0 to 60kmh

[150pcxer]

than from 60kmh and upwards

what's happening?

[Conelite]

0-60 the engine is under much higher load. Once you get past that the engine is able to reach higher RPMs and feels light it smooths out.

Try experimenting with lighter weights or maybe upgrading your Variator if its that much of a concern. I'm sure your bike is fine if its been maintained properly.