The sounds doesn't change much when off throttle. In other words it is constant. When decelerating with the engine running, the sounds intensity seems to be in relation with the speed.
This is what makes me think it could be something like the piston in the cylinder. The new gaskets arrive today so I will be pulling the cover off to snoop around to see if it's bearings, as well as the cylinder and inspecting the piston and cylinder.
Any quicks on what I should look for that might be suspicious?
(maybe I'll try and take a video..)