Starter Spins but Doesn't Turn Over Engine?

[unL33T]

Anyone know what's going on with my friend's bike here?

https://files.catbox.moe/w0oq8p.mp4

 

[POWERMAN]

Battery?

 

[Brian P]

Starter clutch.

Get access to it and check what's going on with the one-way clutch and the geartrain leading to it.

 

[Charles13]

Most bikes have a one way sprag clutch that lets the motor overrun the starter when it starts, when it fails the starter will not engage the crankshaft (but they don’t usually fail suddenly), I’m not sure if this bike has one as I don’t know what bike it is.

 

[Relax]

Most bikes have a one way sprag clutch that lets the motor overrun the starter when it starts, when it fails the starter will not engage the crankshaft (but they don’t usually fail suddenly), I’m not sure if this bike has one as I don’t know what bike it is.

They can when the spring that holds the "teeth" together breaks. Had this happen on my bike - I rode it to work and when I tried starting it to get home, it just spun.

 

[unL33T]

Battery?

Seems like this was it. Worked when boosted. I thought my friend tested this before I asked since it was my first suggestion and they kept asking after.