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Discussion Starter · #1 · (Edited)
Drive Pulley noise? (Video)

There is a high pitched whirring/spinning/cricket? noise that seems to be coming from my Drive pulley. Hard to describe. It is not as easy to hear in the video as it is in person. More pronounced with the belt covers off. It looks like there is a very slow oil leak from behind that pulley as well.
Thoughts?

I have a track day in a few days that I really don't want to miss.

 

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Sure sounds like it's coming from your drive pulley. And it sure sounds like your bearing is failing.
I would remove your belts and see if there is any movement that shouldn't be there to start with.


Paul 03 ST4s, 15 675RX, 96 ZX11, 76 KZ900LTD B-1, 72 SL125
 
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Discussion Starter · #3 ·

Another video. It almost looks like there is some lateral movement at around 13 seconds when I show it from the back.

If that is the case..How big of a job is it? I am guessing I should sit the track day out....
 

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I have never been in there before so I can't say. Look at the parts fische to see the assembly and maybe Google it too. Sorry can't help you any further.

Paul 03 ST4s, 15 675RX, 96 ZX11, 76 KZ900LTD B-1, 72 SL125
 

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Take a long screwdriver and use it as a stethoscope, hold the handle to your ear while touching different spots to pinpoint the noise origin. I'm trying to find the bearing for the timing lay shaft. That is what your drive pulley is mounted on. What year is your 848 though doesn't much matter I'm guessing.

Paul 03 ST4s, 15 675RX, 96 ZX11, 76 KZ900LTD B-1, 72 SL125
 

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My 2012 SF 848 sounds exactly the same if that makes you feel better. I know the belts can make odd noises at different tensions so I'm assuming that was the cause. I can't hear it at all with the covers on.

Check the link (https://photos.app.goo.gl/AWf53Nun2EUzAKg5A)

If this is a sign of a problem I would be interested to know but at 8000 miles I'm not too worried. Any Duc techs that would know for sure?
 

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My 2012 SF 848 sounds exactly the same if that makes you feel better. I know the belts can make odd noises at different tensions so I'm assuming that was the cause. I can't hear it at all with the covers on.

Check the link (https://photos.app.goo.gl/AWf53Nun2EUzAKg5A)

If this is a sign of a problem I would be interested to know but at 8000 miles I'm not too worried. Any Duc techs that would know for sure?
I'm beginning to think it isn't his bearing since the type of bearing used here shouldn't be failing for pretty much the life of the motor IMO. I've never noticed mine making a noise similar to this over the noise of the clutch I guess. And since yours sounds the same it's the belt making the longer turn around the drive pulley that could be creating the sound he's hearing. Your bike does sound the same (metallic). Good looking bike also!

Paul 03 ST4s, 15 675RX, 96 ZX11, 76 KZ900LTD B-1, 72 SL125
 

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Could that whining and chirping sound be the Shift Fork and/or a broken Shift Fork Spring dragging against the Layshaft Gear?

I wonder if this Youtube video I found is addressing the same problem -

Here is a video he posted of the sound caused by the Shift Fork on the Layshaft Gear -


To my ears it does not sound like the same problem. I'm still thinking it's just the sound of the belts and nothing to worry about.
 

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Mine is a 2v, with a simpler belt layout, but I had a very similar noise, but only when the motor was cold. I pulled the belt covers and noticed the bearing across from the tensioner bearing was spinning just slightly slower than the tensioner. When warm, it spun the same and the noise was gone. This was the vertical cylinder, so the belt is quite a bit tighter when warm. I checked the tension, and sure enough it was a bit loose. Not loose enough to be scary, but I'd prefer perfect tension. A quick adjustment and it hasn't made a noise since. They aren't silent, of course, but just standard belt noise is left.
 

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Belts can chirp when they are old particularly when cold, often goes away when warm. The other common cause is water and as already mentioned to loose tension.
Failed idler bearings make a growling sound. Replacing bearings and/or belts is fairly easy for anyone handy with spanners but need to be careful of timing so follow manual or videos etc.
 

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Yes, idler pulleys can fail.
Which just happened to my ST4s,
better safe than sorry..
Not to expensive and cheaper than bent valves..

Andrew
 

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Hi. I had the same idea, the ring seems to emit a similar sound. Did you confirm it somehow?

I noticed that your engine has a light whirring sound, is it maybe the reason you opened the engine?

Thank you!
 
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