Any bike will do

What is the proper motorcycle to ride around the world ?
Any mid sized or larger adventure motorcycles will do well. From Honda CB500X, Kawasaki Versys650, Yamaha T700, Aprilia Touareg 660,  BMW F850, Tiger 900 ralley to Honda African Twin 1100, BMW 1250GS and Tiger 1200 ralley pro. Take any one of them as you like, these bikes all have good reputation being reliable and robust. This is not an easy trip for novice riders, you need to have at least 5000 kilometers ridden on varied road surfaces in the past and keep riding recently.  It is highly recommended that you take a riding course if you are new to big bikes. Once you are confident riding big bikes then you need to do some regular exercises like running or cycling to maintain a certain level of endurance. On some days we need to ride a whole long day in extremely hot or cold weather.  This then can be done and enjoyed if you also bring a little bit of spirit of adventure and a sense of haha.