I try to find out where the buzzing noise out of my motor is comming from. You hopefully can hear it in the videos attached. It appears only at idle. At higher rpm´s, it disappears. Where the hell can it come from?
Isn´t a defect cranck bearing sounding different? Maybe too much side-tension between the main bearings ?
Every help is appreciated

Had other noises as well, therefore i separated the cranck and the gearbox by pulling off the clutch basket. The reason for another,a ticking noise, i might have found. The brass bearing inside the clutch basket was quite lose, so i replaced it by the brass rings from a brand new basket. It has less play, now on the bushing.

Sounds a little like an alternator that's charging hard.  Might be the ignition?  Does the sound change if you disconnect the wires from the regulator/rectifier (if it's a Powerdynamo/VAPE...  it looks like it is)

Interesting, & i'll be the dummy--how did you start it minus all the bits, like to see a short video of that. Anyway--noise, i wonder if its got a standard clearance bearing on the left & should be extra clearance, "clearance of the balls in the race & not of the fit in the case". Reason i say that is the left is expanded by the super tight fit on the shaft & compressed by the tight fit in the case. Where the right side is a slide fit on the shaft so only outer is compressed. Right side held tight by the crank gear & nut. So a C3 or C4 might be the answer for the left main. Only guessing of course.

I am thinking bad crankshaft main bearings perhaps. does it sound rough when you are kicking it over or turning the flywheel by hand?

I would check it for play on both the mag side and primary side and check for the presence of oil, it would be wise to replace the crankshaft seals too. the cases will need to be split to replace the main bearings.

on the flywheel side you can try picking up on the flywheel and see if you feel play in your hand. if it is loose I recommend replacing both bearings as a set. www.wiseco.com/Catalogs/Powersports/CompleteCatalog.pdf

looks like your bike takes BK5002 if you need it.

Yep, i just to clarify my post, i meant Squeezed too tight but still smooth, not through the hardening as such. But try unhooking the charging as i think Mark said. Be interesting.

My thought on bearing was crank seal pressed in too far cutting off oil to outside of bearing. 

My hope is it's an electrical noise of some kind...  maybe output of alternator is shorted or something?  A car alternator can make a similar sound and it's not the bearings.

Maybe that's how the left side sounds with the cover off? I'd be interested in the sound LH cover on.

Without knowing how far apart the engine was, meaning, was the crank big end replaced? Thrust washer/clearance issues? If not, did you have good clearances between crank halves & cases once the cases were assembled? Were the cases split? Rust build up on the field shoes?  Random thoughts....

have you had flywheel off to see if any signs of rubbing exist?
If no rubbing and noise does not change with charging coils disconnected then I think you have a bum bearing which is a bummer because your motor sounds pretty darn nice minus the screetch 

how did you start engine?

Probably with a belt around the flywheel and either a high torque electric motor or a running engine from another source.