2018 EC 300 not running well

[eralha]

Hi,
Last ride my bike started running bad, like its in a rich condition, i didn?t change anything it just starter doing that after a hard ride.
Next morning e took it for a ride again and changed the spark plug, it got a little better but the problem maintained, at the end of the morning the problem got a little wrost.

Took it apart and cleaned the carb and check the reeds all seems good, the problem is still there, i'm thinking if it can be something on the cilinder or piston or even crank seals.

Can some one point me on the right direction?

Thanks.