FE650 sounds supercharged

Hello all, this is my first post on here so please bear with me if I ramble or do not include enough info.
I am having a problem with my ’07 FE650. Basically, when running, the bike sounds like it is supercharged. There is a high pitched whining coming from the motor. Seems to be coming more from the bottom than the top but difficult to tell. The whining increases and decreases with engine RPM and is always there. Pulling the clutch in has no effect.
When I first took the bike to the mechanic he thought it was the timing chain as it was loose and due for replacement, so after replacing it and doing a few other bits and pieces (general service stuff) I took the bike back and the noise had gone. The bike behaved perfectly for the first ride after getting this done and I thought all was good. However, this Saturday just gone I took it out for the second ride since the timing chain had been replaced. Took the bike off the trailer, started it and low and behold, the supercharger noise is back. Oil has been changed and coolant level has been checked and both seem normal. I just got back from the mechanics and he is stumped. Did not seem to think it was going to detonate but could not recognise the noise. Now I am getting a little desperate as I have just spent 3K getting the thing back up to scratch (or so I thought).
I was talking to a guy on the weekend who mentioned that he once heard the same noise ( all be it a little louder than my bike ) coming from another FE650 so I am hoping that this problem might be known about.
If there is any more info that would be useful to know, let me know and I’ll post up
Any help anyone could offer would be greatly appreciated.
Thanks people.

Thanks Taffy,
Have done two oil changes since the noise first appeared and there was only the normal (minimal) amount of material collected on the drain plug, nothing in the oil screen and the filter appeared to look normal. Would it be fair enough to say that if it were a crank about to break or another main bearing in the engine about to go, the sound would not have gone away and then come back like it did ? or am I just being optimistic ?

Bofwool said:

They chirp like a big canary mate. Its the carby slider flapping so they tell me. You grow to love it.

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He he. They sure do. And I already love that sounds. But this is something different altogether. Its like a high speed whin, not so much a chirppy flutter.

Thanks for the responses guys. I've passed the info on to the mechanic to see if he can check any of the things metioned. I'll let you guys know if I manage to get the to bottom of it.

In the mean time, if there are any more suggestions, keep em coming.

Thanks again all.

squizz said:

get a recording of it and post it on here. It may well jut be the straight cut gearing noise that they have.

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Great idea squizz, I did not think of that. I'll try to get something decent to record it on and post it up if I can.

This noise is definately out of th ordinary though. Been around Bergs for quite a few years and never heard one making the noise mine is now making..

I should be able to get a recording up on Sunday. Hopefully that will give you guys a better idea of what I am on about.