My old scooter making a weird noise while accelerating

In the video it seems to be an ingition problem to me.

Try to pull out the connector from the CDI signal unit and the CDI unit maybe the ignition transformator, clean it with contact cleaner than put it back.

If you have a new variator kit the noise can be from the clutch drive shaft, remove the clutch block and pull the drive shaft forward and back by twisted left and right if it moves forward and backward than you have an internal broken circle clip, this circle clip on the drive shaft beyond the gearbox crankcase it is important it keeps the clutch pulley and the belt in line with the variator once the nut is tight up. If this internal metal circle clip it is broken than the drive shaft will move forward when you tight the nut and consequently the clutch and belt are not in line with the variator, basically the belt will works a 0.5/1cm maybe more sideway and once the temperature raise the pulleys and the rollers suffer because it is not opening in parallel and all is compromised in acceleration and deceleration on the clutch pulley as well. The clutch drive shaft it is hold in place by two circle clip, one internal beyond the gearbox crankcase and one external the length of it will be at the correct alignment once the belt is on the clutch pulley. I manage to resolve the problem on my Gilera by removing the nut and let the entire metal cart to hold the clutch drive shaft because the clutch has an anti centrifugal force and tend to push on internal way and not on external way, I also put a little rubber wash on the driveshaft before install the cart just to stop the drive shaft to hit the bearing on the cart cart, not need but in deceleration the clutch has a little centrifugal force versus external so in case a put one slim rubber gasket around the end of driveshaft. Why this metal clip is broken? mainly because when the garage service the variator rollers they do not use a dynamometric spanner they tight the clutch nut with tyre gun and this in short time will brake the metal clip because this big nut it pull in opposite direction and unfortunately to replace those metal clip all the engine need to be dismantle, this final and last nut it only need 30-25newton/m and the tyre gun it is well over 100newton/m