The whining noise in the 650 and many other motorcycles is caused by the straight cut gears, in the engine and the transmission.
When you pull in the clutch the transmission free-wheels, there is zero torque on the gears (being spun by the output shaft to the back wheel). That is why it goes quiet.
Some higher end bikes use helical cut gears exactly for this issue. The yamaha FJR-1300 was revised a few years ago to change the transmission from straight to helical cut gears, and it is a big selling point for the new versions of the bike.
I dont know if there is anything with the weight of the oil you are using, or if something else on your bike could also be whining or whistling to make a noise like the bike in the video.
One thing to verify: when you use foam ear plugs you have to squish them up and push them in your ear, and then stand there and hold it pushed into your ear with your finger, until the foam has minute to expand into place. If you dont do that they dont block sound very well. When they are correctly inserted your ear will feel plugged, like there is water in your ear.
A good test, if you can hear your stock horn at 55mph on the bike your ear plugs are not working.
I have a hearing loss and I cant wear my hearing aids and my glasses at the same time with my helmet, so I normally dont wear the hearing aids. The few times when I rode with them the bike sounds very loud!
The only other thing I can suggest is to make sure your final drive from the drive shaft to the back wheel is full and has the correct 80W oil.
how many miles / km are on your 650? As bikes get used the gears wear more and get louder.
Last edited by KCW; 08-02-2018 at 09:52 PM.