We had a 2018 engine on the bench and its bearings had no plastic cages. It was the first time the engine was opened. Unfortunately I had not taken any pics but couldn't know that this will be a point of discussion in the future.
In the meantime I learned that the N1EF is far less than ideal. After many hours of testing for my riding style (slow mid-technical in gears 1,2,3) I have found the following set up to have least low down blubber and best, crisp throttle response:
NEDW (half clip richer than the above mentioned...
Same here. 4 bikes two 18's and two 19's they all had it. Made me crazy but now living with it.
I think it is pipe bang, most of the time it appears when going steady and slowly or inadvertently close the throttle just a tiny bit. Bang! Sounds like a hard knock and comes from the cylinder...
As said on thumper talk, that bike has been left sitting with water in the engine, maybe by a previous owner. The corrosion in the case where the main bearing sits is severe.
Such a corrosion will not happen in a day or two, not even in a few weeks.
That your carb doesn't react on the As has nothing to do with the float height nor with the needle.
First look what is installed and let us know, then adjust float height and when you do so check float valve. Check how far the slide is lifted by the idle screw.
Turning in the AS all the way...