I took a honda PA50II moped in/out of my basement last year. Getting it out was actually way easier than getting it down. Getting it out, I got a long board and just pushed it up the stairs on the board. This moped was about at the top end weightwise for what I could push by hand, but I bet using a winch you could slowly pull it out and have a person or two to guide it on the board. The board obviously needs to be very secure, especially at the bottom-- it could just slide straight out from under you. I got away with just the board, but you probably should build some sort of track to keep the wheels straight. Something like a "U" shape track. Once you have your track in place, test it with a bicycle by hand to get a sense for how the bike will look getting on/off the board. With the moped, the hardest part was at the top of the stairs, because once the front wheel made it on the flat floor, there wasn't enough clearance between the bottom of the bike and the first step and I had to lift it by hand. This was very difficult since I was pretty worn out from pushing a stupid moped up the stairs. So pay attention to this clearance, and make a plan for how to address the clearance problem, because there most likely will be one. The top is going to be the most awkward point so it's the most crucial to plan for. Removing the handlebars is a good idea since they are inevitably going to get in the way.
Also, verify that your stairs are going to handle the weight. Mine were fine for the moped but I'm sure that they would crack from under me with a big motorcycle. Figuring out how to get someone with a crushed spine to the ambulance without a complete set of stairs is probably a challenge.
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All in all, getting it up the stairs I think would not be dangerous as long as you have your winch secured to the bike and a good track to stop it from slipping out from under you. The worst realistic cases all involve your bike getting messed up, but not you if you have a careful plan.
As far as getting it down the stairs, though, that might be tougher. The way the moped got down the stairs involved me trying to slowly push it down the stairs. This worked for about 3 steps until gravity took over and after that it was very easy.
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I could see you using this same track/winch approach to guide it down but I can't speak on experience on that one. If you were to do this, I'd recommend taking it down backwards and of course not getting on the bottom of it while it's going down.
Up and Down are both going to require you to have other people around to help. Obviously, I would imagine getting the engine off of it and moving this separately (dolly?) would make things way easier weight-wise...