Strange clicking & clunking from gearbox under load VFR800X 2015 55k

[Wideboyracer]

Hi people
My new to me 2015 CR.
55k miles
Full service history.

It is making a clunking noise under load from the sprocket/gearbox.
I have uploaded a clip. Listen for the irregular metallic click behind the engine and chain noise.

The chain was slack. I had it tensioned by the local bike mechanic. Now the sound is more prominent. It is louder when underway.

My description in the video reads as follows:
I'm hoping someone can tell me what's going on here please. There is a noise coming from the middle of the bike.

The chain was slack, so I thought the noise was from that. The noise was obvious at low speed but went away.

With correct tension on the chain, the noise is worse and present at all engine speeds. The chain is definitely not too tight.

The video clip shows the bike running in first gear on centre stand. Behind all the chain noise, there is a random click, coming from the front sprocket/ spindle gearbox area.

I'm thinking spindle bearing is worn after 55k miles. Or is there a broken tooth rattling around the gearbox (under load the noise is regular, I call it a rotational knocking. It speeds up with engine speed, so I suspect it's not a loose tooth).

Does anyone have any experience of this on their bike? What's the solution please?

[Notgotone]

 not heard anything like that, have you checked the front sprocket for wear and tightness

[Wideboyracer]

I thought it might be a tight spot, given that it got worse with the tighter adjustment. The chain does have uneven tightness but in my 20 years experience with bikes I haven't heard this kind of noise behind the sprocket, and so irregular.

I'm going to get the chain and sprockets replaced to eliminate that as a problem.

[CBM]

It sounds like chain/sprocket slap/noise to me, try running it without the chain whilst changing it and have a listen then.

[gatesy]

Hi wideboy racer,
Strange noise indeed. Try the easier things first is a good motto. Without chain and then with another friends chain if poss before assuming sprocket bearings etc. Experience says it is likely to be outside the engine than deep in the internals i.e. broken cog teeth etc.
If however you have sorted it by now, what was the problem?
John

[Lars]

it does sound a lot like chain to me, I had exactly the same noise before I replaced the kit.
how old is that chain ?