Can you post a link to one of the videos you have seen that shows a Gen2 rotor rotating as revs increase.
Edit: I think that you are confusing the EXUP valve in the exhaust headers of the GEN1 with the exhaust valve fitted to the OEM end can of the GEN2. The valve in the GEN2 is only to reduce exhaust noise within a certain rev range which is why the default setting is open. The valve only closes ~4k to reduce noise and opens again after 5k, in your other thread I posted a video showing this to be the case. The fact that the valve in the GEN2 is in the OEM end can and that no aftermarket end cans for the bike use an exhaust valve would kind of prove that the valve has nothing to do with performance. I'd suggest that if you're not happy with the way the bike performs with the aftermarket end can you should take it to be properly remapped to sort out any fuelling issues. Alternatively refit the stock end can and connect it the servo and you should have a fully functional bike as Yamaha intended barring any other mods that were made before you bought it.
Edit: If you're not happy with that answer you could always contact Yamaha to ask for confirmation - General Support & Enquiries - Yamaha Motor (yamaha-motor.eu)
Edit: I think that you are confusing the EXUP valve in the exhaust headers of the GEN1 with the exhaust valve fitted to the OEM end can of the GEN2. The valve in the GEN2 is only to reduce exhaust noise within a certain rev range which is why the default setting is open. The valve only closes ~4k to reduce noise and opens again after 5k, in your other thread I posted a video showing this to be the case. The fact that the valve in the GEN2 is in the OEM end can and that no aftermarket end cans for the bike use an exhaust valve would kind of prove that the valve has nothing to do with performance. I'd suggest that if you're not happy with the way the bike performs with the aftermarket end can you should take it to be properly remapped to sort out any fuelling issues. Alternatively refit the stock end can and connect it the servo and you should have a fully functional bike as Yamaha intended barring any other mods that were made before you bought it.
Edit: If you're not happy with that answer you could always contact Yamaha to ask for confirmation - General Support & Enquiries - Yamaha Motor (yamaha-motor.eu)