People circumnavigate the globe on all sorts, from Honda Cubs to fully-laden BMW GS’s. Whatever you do it’s a trade-off. Smaller bikes are lighter and potentially simpler, large machines are more comfortable and carry more gear with less stress. Do the pros outweigh the cons for either? Is there a sweet spot in between?
The engine is running, you’re pointing east ready for the adventure of a lifetime. What bike are you sat on?
Maeving RM1 
Don’t start!! 
Twat… 
Whatever bike I own at the time. You can try to circumnavigate the world on any bike. It’s been done on old Suzuki DRs. BMW GS of different capacities. Someone did it on an R1. Ted Simon used a Bonneville the first time. There’s a man trying it on a battery bike at the moment.
Probably for choice I would have a smallish capacity bike with very little or preferably no electronics.
My old XT500.
Ok, just for discussion’s sake…
Electricity can be (and is) manufactured globally.
What better way to meet people and actually experience the world than having to stop every 80 miles and meet up with people to solve the issue of changing the local power supply into one that suits your charger?
*40 miles…probably 
Theoretically a nice idea but it assumes you’re 80 miles from the nearest person (with electricity) at all times. I would say that having no one around for at least 80 miles was part of the reason for going.
Solo? CG125
With Pillion? Africa Twin
Good choices, I reckon. As long as you’re not in a hurry on your Honda.
Well obviously for me it would have to be my 650 VStrom. It’s already proved it can do the job by taking me to the Nordkapp and back in 2019 with the only maintenance required being a chain adjustment.
Mind you as I get older the VStrom is becoming heavier and heavier to move around so I might go for a 300 - 400cc bike, or possibly even a 250cc
Charley and Ewan had a go at that on H-D LiveWires. 
Not their finest hour.
My initial thoughts on this was to go with my tiger sport. But taking a step back and giving it some more thought I think I would go with a Royal Enfield Himalayan. Simple engineering, good luggage capabilities and with enough power to get along at a reasonable pace both on and off road.
My daughter on her round the world trip has been hiring 125 scooters at av $6 per day in east Asia, she says they’re proving ideal for the roads and traffic, probably a sensible choice
Royal Enfield Himalayan. 411cc’s of pulsating power !
Plus it’s been to be up to the task by many world travellers including “Itchy Boots”.
Hasn’t Itchy Boots also been using a Honda CRF300 - That looks ideal as well.
I think my Tiger 900 Rally Pro could get the job done, but I wouldn’t trust all the complex electronics to last the course.
Honda cub 90.
Guaranteed spares wherever you are!
Here’s a coincidence. I was just chatting to a fella I’ve never seen before in my local about half an hour ago and he was talking about itchy boots. I made a note to look her up.
My mate has a Himalayan and swears by it. @Motopulcino tried one at the bike show last November and really liked it, too.
As long as it’s on tarmac roads and involves a 4* hotel each day, I’m not really that fussy!