Originally Posted by Pantah
For adventure travel, I vote for the biggest motorcycle you can pick up out of the mud solo.
That's it - the one factor that determines it.
Adventure is doing something that turns out not the way you expected but works out ok in the end. By that definition riding a 500 lb plus, 100 hp plus basically on one wheel, into the unknown, with untested abilities qualifies, as high probabilty adventure, but high probability tragedy too. If the bike is stuck, or you are stuck under it the bike adventure is over for you, unless trying to walk 50 miles, is the adventure you are looking for, or maybe it's a grown up game of hide and seek with emergency rescue. You don't need a motorcycle for those adventures.
For most people though, it's about riding the bike, the adventure comes as a consequence of where you have to ride to get a type of riding experience. Defintely the lighter, and with sufficient power (60 hp, roads with traffic, 40hp no traffic), the bike is, the more fun, technical, challenging, and rewarding the riding is.
The adventure is when unexpected uncontrolled things happen, big bikes on pavement at highway speeds tend to have very short adventures.