Clunking sound

[blind]

When accelerating in first and second gear, I hear 2 or so clunks (metal to metal) sound coming from my left foot.

Could this be chain tension to loose?

I manually checked the tension and it does seem a bit loose.

The clunks are intermittent.

 

[Deleted member 1183]

Hmm. This seems to be a regular issue with this bike when the chain is getting old. I had exactly the same problem with mine and it was really bugging me for a long time. I felt my chain was ok, yet it continued to happen. I will guess that you have at least 20,000 kms on your chain or thereabouts ? A replacement chain and sprockets got rid of it for me.

My original chain was ok at that mileage. There was some wear on the sprockets and it was well lubed but there were some tight spots. However I still felt it had some life in it. Eventually my Tech persuaded me to put on a new chain and sprockets and the noise went away.

I tried to rationalise this. I believe it is down to the fact that the NC has a floating front sprocket. That means it is free to move on its splines. When the chain gets tight spots with age, I believe the tight area of the chain causes the front sprocket to rattle momentarily on its splines due to the minute change in chain velocity as its tight spot passes over the teeth of the sprocket. That is all I can think of. If you listen carefully the knocks will coincide with each full revolution of the chain over the front sprocket. Usually when the chain warms up sufficiently, the sound almost disappears.

Anyway, my Tech suggested that the chain was giving me a warning. He suggested that I should heed the warning as otherwise the next communication from the chain might be disastrous. If you have a relatively low mileage chain then I would have to question your maintenance of it.

 

[Gigs]

Mine will do that at high mileage on the chain. Lube and adjustment usually clear it up. I think it's chain slap.


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[Ed Up]

Mine did that, tightened the chain and poof the slap was gone.

 

[Deleted member 1183]

If lubing cleared it up it would be fine. Furthermore what I was hearing was not chain slap. It was a dull knock as if it was coming from inside the gearbox in 1st and 2nd. One or two others on here have experienced this also.

I could not get rid of it at the time, no matter what I did. There is an oiler on my bike so the chain is always well lubed. I tried tightening the chain, loosening it, checked everything possible that could be causing the knock, but in the end it was just a worn chain and replacing it sorted the problem.

 

[blind]

Thanks for the replies. 15k km on the bike and I just bought it. Will adjust chain and check. Replace then if it doesnt stop.