Stutter and violent vibrations - Cylinder 2 and 4 not firing up

[ozanec123]

Changing the spark plugs would do any harm just to rule them out.
However 2 and 4 would probably be a carburettor  problem rather than coil or spark plug as 1&4 share the same coil and 2&3 share the same coil
Was the bike left unused for a long time?

Wouldnt say unused very long time, just few weeks probably, and kept in the garage, so no idea how could that impact it. The carbs have been cleaner recently too, though not sure if everything was done correctly there.