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Just this last week I noticed an odd sound at idle at several red traffic lights. It sounded then like a dry, spinning noise. I couldn't immediately determine where in the engine it might be because it seems to echo through the whole engine. At higher rpm would go away. I changed the oil today (didn't see any flecks in the oil, but did notice a little gasoline smell to the oil, and it did seem to have some gas in it)and started it up, but the dry, spinning has turned more like a grinding noise. At 3000 rpm it goes away, and the motor sounds as normal...under 3000 rpm the noise returns. Could that be a timing chain being loose, or does that sound more like a bearing going out inside the engine? Thoughts appreciated.
 

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A mechanics stethoscope might help locate the source of the noise if it persists after cam chain adjustment. Not expensive on eBay and handy for many automotive uses.
 

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You only hear the noise when stopped and lower rpm’s? Is the noise the same with the clutch engaged and disengaged? Do you still have the old oil filter? If so cut it open and look for metal bits. If your timing chain was loose enough to make this much noise I would expect to find metal bits from the chain hitting the case and bolt at that location.
 

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FWIW-if the noise isn't isolated to the engine rear(use a stethoscope as suggested)...oil pump chain could be a possibility.....
too loose it can scrape/hit things in the vicinity of the clutch basket......
 

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Just this last week I noticed an odd sound at idle at several red traffic lights. It sounded then like a dry, spinning noise. I couldn't immediately determine where in the engine it might be because it seems to echo through the whole engine. At higher rpm would go away. I changed the oil today (didn't see any flecks in the oil, but did notice a little gasoline smell to the oil, and it did seem to have some gas in it)and started it up, but the dry, spinning has turned more like a grinding noise. At 3000 rpm it goes away, and the motor sounds as normal...under 3000 rpm the noise returns. Could that be a timing chain being loose, or does that sound more like a bearing going out inside the engine? Thoughts appreciated.
Could or be the rpm gauge cable or speedometer cable? Try disconnecting then getting the gauges. They happened to me.
 

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Came here to post about the tacho drive - I had something similar on an old GS750 that ended up being the bushings in the tach wore out, and stuff started rubbing and making grinding noises that I just couldn't hear at higher revs.
 
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