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[mistasam]

So I went for a ride, totally find, nothing weird about it, had a lot of fun.  Decided to go back out and do the same run and I noticed a weird thumping noise.. like I was driving a car with a loose wheel.  It SOUNDS like it's coming from the motor, but I have no clue.  Here's a video of it:



Anybody heard this before, or have any ideas what it might be?

[BrianTRice@gmail.com]

That does sound like a wobble of some kind. Check the belt tightness and alignment, perhaps. Or have a mechanic / service tech look at it.

Maybe check for debris in the countersprocket just in case.

[mistasam]

Yikes.. I'll put it up on a stand today and see what the belt is doing.  Hopefully it's a quick fix.  Weird that it just started doing this.

[mistasam]

Well, I jacked the bike up and spun the rear wheel.  The sound is definitely coming from the motor area.  The front sprocket looked fine (no rocks/twigs/misalignment) and the belt is tight, although I don't have a tension gauge yet.  So I'm assuming it's inside the motor.. maybe the shaft itself?  I'll upload another video of it tonight, but it's basically the same sound.

[firepower]

loose shaft will clunk on acceleration and deceleration. usually a loose set screw.

[mistasam]

loose shaft will clunk on acceleration and deceleration. usually a loose set screw.

The screw at the end of it, on the other side of the sprocket?

[mistasam]

Ok, I'm pretty sure the front sprocket is loose, so I'm going to loosen the belt and try to fix it.  Anyone know what torque to tighten it to?  And any tips on how to make sure everything is aligned correctly?  Cheers!

[mistasam]

Just wanted to update this and say that the belt was about 10kg tighter than it should have been.  The noise is almost completely gone now and it runs a lot smoother