Thanks!
Since it would be illegal to ride her now (I would pay a fine and lose insurance if caught) I just put her into the garage again after a few minutes.
I also don’t trust the oil, I don’t want to risk damage to the engine.
Next step will be changing the oil and the brake fluid I guess, and lubricate the chain a bit more than it is now.
Then I might already be set to get her to the TÜV to check her and regain the permission to ride.
Understood. I thought that you had changed the oil and filter. Good luck with all, including the TÜV.
Empty carbs, they had to fill up first. You now need to put some miles on it after you get it idling for a bit to see how they settle. Carbs can be a bit finnicky but so much fun once you understand them!
Some other advice, use a engine flush with the old oil, let it run for 15 minutes and then change the oil. It should remove some settled dirt from the engine. Also don’t forget about the filter!
Letting the engine run up should also show you if the fans that are behind the radiator still trigger, though I am not sure if this Honda model has that!
Air filter might need some love too! and be sure to check for any signs of leaks or sweating of oil or fuel, when you let it idle for a while then you can see what happens when oil pressure and temperature builds up!
Update:
With a little help from my brother I changed the oil.
What came out of the bike looked perfect though, none of the typical signs of bad oil.
I could probably just have left it in there. But better safe than sorry.
The new oil is a partly synthetic 10w40 as the manufacturer recommends. I double checked that with the guy from the repair shop.
I also got a new aluminium seal ring for the oil drain plug, just to be sure.
As you (and my brother) suggested we let the engine run for a few minutes before changing the oil, and after five minutes or so the sound of the engine went from slightly stuttering to perfectly smooth. I could even push back the choke a bit and it was still fine.
After we had changed the oil we also let it run for a bit, then checked for leaks. None. I checked again the next day, but still none.
So today I put everything together again, and I even found spots for all the bolts and screws and stuff, none left after assembling the bike again! 
So next up:
And then once that all works:
Yeah baby! That’s the Honda feeling 
Gah, another two weeks went by since my last post and all I did was order some lubricant for the chain.
It have been a few busy weeks. Still confident I might get it to the TÜV before this month is over.
Nice! I’ve got a new fixxer upper, a CB750 that has been standing idle for 7 years… Going to strip it down to the block and then see if I can get it cranking again. Empty a can of WD40 in the cylinders, next day some diesel fuel, and another 48 hours later some oil and see if I can get it cranking.
The oil looked think black, so no ingestion of moisture which is good! Other then that… We’ll see…
The CB750 is a fine motorbike. 
It is! I’ve already got one, but the fixxer upper is a 81, and my current one is a 95, lowered a bit at the front end and custom suspension at the back(original cylinders started leaking, though no degradation in performance weirdly enough).
Wow, I really forgot to post the result here!
Three weeks ago I finally lubricated the chain, and then called the shop. They fetched the motorbike, changed brake fluid and coolant, checked that all the things I did were OK. Then I got the TÜV certification.
…and since then there was always bad weather when I had time to ride, so all I did was ride her home…
But hey, I have a working motorbike again!
Great. Now you can put it into hibernation
Yeah, pretty much. But then, maybe there will be a few nice days in winter, I had that before. I remember having a nice ride in November a few years ago, and one in January, too.
Today was a nice day, But since I haven’t bought a new helmet yet I decided to spend the afternoon with X-plane.