@madin :It's a combination of too much added copper and too little space
I removed the large bearing and found it was crunching quite a lot. It's a quality NSK bearing but it's only sealed ZZ (metal plates) so i guess the chain has put gravel and salt into it last winter.
I ordered a new bearing from vxb bearing: 61810-2rz
It's 5mm thinner and only 65 OD. I'll make a shim ring for it that is 65/72mm and 7mm thick.
It has two low friction rubber seals. An SKF bearing of this type adds only 5W drag at 3000 rpm, very low!
I'll check the space for those of you that won't change bearing type. I think it's possible even without the milling of the bearing seat..
It won't be possible to squeeze the end turns to get more space, only by squashing the phase leads better. We'll see.