Ignition problems

[SundayMechanic]

https://youtu.be/laVtrzh7SGo?si=6tPWE-Q8Dyrwi8Yu
Any idea how to address this problem? Sounds lumpy at low revs like misfiring. This happened after carb clean. Mech says it might be bad ignition timing or something with valves, bike has been sitting still for quite a while and had some other problems beforehand. Those I sort of dealt by myself, one way clutch bearing change. Could the also be a stator problem? Or maybe carb? Any suggestions what to do? I'm a really bad mechanic so dumb it down for me please, if you can.