Clunking when pulling away & off throttle at low revs. VIDEO

[powerbio]

As if the first lot of problems weren't enough, my bike has a clunking type feel/sound when pulling away slowly. The noise and feeling goes away once i get up to a little bit of speed
When it occurs, if I pull the clutch in it disappears.
It also occurs when I'm in a high gear with low revs and I open the throttle.

I had the front sprocket, rear sprocket and chain replaced with oem (fs) and Renthal (rs & chain) around 3000km ago.

I had this issue before I stopped riding the bike 5 years ago and it seems to be a little worse now having ridden it today.

Potentially chain problem?
Are there any bearings for the front sprocket?

Sorry to be asking for help again,
Many thanks.

[Dynamohum]

Do you get a shudder vibration noise when releasing the clutch when moving off from standstill ?

[powerbio]

Hi there,
A little bit yes.

So I've done some more investigation work.

With the bike up on the paddock stand, engine off and clutch pulled in, when turning the back wheel I can feel the clunking through the handle bars/clutch lever. Per one rotation I can feel about 3 clunk's...varying in intensity.

I loosened the chain to see if it was chain tension, made no odds.

I decided to then see if it made the clunk's when in gear so again with the engine off, pulled the clutch in, selected first gear, clutch out, turned the rear wheel to confirm gear selection had been made. Pulled the clutch lever in to allow the rear wheel to turn again to check for the noise/feeling and the back wheel wouldn't rotate. The clutch has stopped working.
I had no gear changing problems when I rode it yesterday but maybe with the engine running it allowed the gear changing to happen?

I'm thinking clutch is the culprit. I installed a decent uprated clutch when I first did the bike up.

Thanks

[powerbio]

Other points to be made...

No clutch slip
Bite point is mid way on the lever
Had a quick check and looks like clutch cable actuator arm is being pulled fully round and returning to correct start position.

[magg]

First test I believe would not turn clutch, as gearbox was in neutral. Pulling the clutch lever pulled in would have little effect. Only the gearbox output shaft would have been rotating.

Second test with a gear selected and clutch lever pulled in would attempt to rotate the clutch but I doubt you could because clutch drag common to NCs would mean you are trying to rotate the engine. The clutch has not necessarily stopped working.

Results of your tests suggest that the clunks are from the gearbox output shaft, maybe a bad bearing.

[powerbio]

Thank you Magg,
How worst case is that scenario?

[magg]

Although the chain and sprockets are effectively new, as a further test I would suggest removing them and simply rotate the dive sprocket with the gearbox in neutral. Eliminates the chain and sprockets as the possible source. Even a loose chain could still be the noise/vibration source.

Noise occurs in all gears and is stronger under load but diminished when cruising or on light throttle?

Dud bearing is split cases unfortunately.

[powerbio]

The noise/feeling is worst when pulling away in first gear slowly and once the clutch is fully out. So for example when in slow traffic so moving slowly with low revs.
Also happens when in a high gear and almost going a bit slow for that gear ie low revs.

So yes noise in all gears, stronger under load and OK when riding with some throttle.

Thanks

[Dynamohum]

Had issues not to disimilar to what you describe would get clutch cover off check small outer bearing and clutch nut is staked tight then grab clutch basket and see if there is any excessive movement up or down .

[powerbio]

OK cheers mate,
Been a long time since I worked on the clutch lol