Strange running noise

When my scooter is cold it makes this weird howl. From about the 11th second it starts. Can anyone tell me what that is? When the scooter warms up after about 3-4 km the noise is gone.

https://www.youtube.com/shorts/8y2PcXJ8lqM

Sounds like either the belt or a bearing. In the CVT transmission the belt and pulleys are always spinning with the engine. Given the noise only started after you revved the engine I would say it is a harmonic between the belt and pulley. How old is the belt?

Thanks for your answer. I don't think it's coming from the engine either. I was thinking the belt, or the roller bearing that's on the cover. The belt is a JT Belt and was changed 2 years ago and about 3000 km.

The tone of the howl seems to change as the speed of the rear wheel changes. If that is true, it could be the cover bearing, an axle bearing, or something in the final reduction unit. Even if you have had no oil leak, a first easy check is final reduction oil level. Of course, oil will not fix a damaged bearing.

The cover bearing is a ball bearing and you can tell a lot about those by turning the inner race with a finger. You should hear no noise and you should feel no roughness at all.

I've been wanting to replace that bearing in the rear of the cover. I remembered about a toilet paper method and then came across this video using bread:

https://www.youtube.com/watch?v=7XDbdQv9E2E

It seems to easy to be true.

Just my penny's worth.

Stick to a proper puller for the size of bearing your on about Chris, the casings is very thin because of the extruded shape around the bearing. You can probably hire a blind set from a hire shop.
Even a cheap extractor would be better than hammering bread, or putty, or toilet paper.

Hope this helps.

Be safe, be seen!

.....so are you sure it's the camp?

Won't the hole through the cover preclude using a bread type method?  I have used that method on other tasks with grease and a wooden dowel when the bearing had a seal on the back side.  I had access to a lathe so I could cut the dowel for a close fit.

When my time comes to replace that cover bearing I will try a heat gun then turn the cover over and tap it on the floor.  Inertia can often be your friend.