Here's what I did.
I used a piece of rope and a "rope rachet". Search the web to see what I mean, you can buy them at the hardware store.
Loop the rope behind your rear shock towers, and in front of the airbox over the carb boots. Pull the rope super tight, which pulls the airbox back to the frame and holds it there. The rope rachet keeps the rope tight, so you can do it alone.
Now, you have just enough room to pull carbs back and slide them out the side.
I got them out in 10 minutes the second time.
On the 650, make DAMN sure you have disconnected the choke cable, and using a piece of wire tie the PLASTIC choke arm in the fully on position to get it out of the way. If you don't and it snags on the airbox boots, it'll snap it.
You cannot buy this part. I had to wire mine back together, and actually had another forum member machine a replacement for me. The wired one is still working but could break at any time. Be careful.
Zeke
F'ing stupid honda plastic @#$%! choke lever.