Oh come on guys - This chap posted this thread over a week ago and no one has taken the time to reply! He's even taken the time to post a pic of his bike...
What you need to remember above everything is that some nutters have toured the world on a 50cc MOPED!
I understand that the Honda C50/C70/C90 has been RTW many many times and that it proved bulletproof reliable.
I read a guy recently traveled from Australia to the UK on a flipping 100cc ex postman's bike.
I very much admire anyone prepared to do such a thing!
This means that your Nighthawk 250cc bike is probably more than capable of taking you this distance
. Whether or not it will do so reliably or in comfort is a different thing?
You mention a bad back. I too have a bad back (fractured spine in 3 places, spinal fusions etc... etc...). This is the single reason why I can no longer ride a bike over a long distance. These days I come here to the HUBB just to dream and to remember the good old days when I used to tour round Europe and Africa.
Sorry to deflate your enthusiasm but having a badly injured back isn't a good start bearing in mind your intention (or dream). Perhaps you should instead get a plane there and then simply hire a bike to tour when you get there?
You will need to be rider fit for such a journey. I can't ride longer than 100 miles without 12 hours bed rest.
If you really are serious about doing this then you need to give the choice of bike very serious thought. Not only will you need it to carry you a huge distance, you will need it to carry your luggage a huge distance. A 250cc will NOT do this in comfort unless you are just taking your underpants and credit card.
Personally if I were you I would be reading this forum over and over again. Try and find out what others are doing and have done. Learn by their mistakes.
I don't know much about the bike you mention therefore I'm not qualified to comment in this respect.
Remember the bike you use needs to be bulletproof reliable
. Next is ease of repair (and botching), servicing and finally ease of getting spare parts.
Not much point breaking down in the middle of nowhere if the locals have never seen the bike you are riding.
You are probably better using something more akin to RTW travel. Your budget will dictate which bikes to look at. If you have a limited budget you should look at older models such as the Yamaha XT600E which is a legendary RTW trail bike. Other alternatives include Honda XR650, Kawasaki KLR 650...
You can buy a MINT condition, low mileage Yamaha XT600E in the UK for less then £2,000. This bike = outstanding value compared to more modern and expensive options.
If you have a healthy budget to spend then you can look at newer models such as the Yamaha XT660 Tenere (£5,000 plus for a good one).
Plenty of riders have done a RTW on smaller capacity bikes like your 250cc Honda. A few years ago the little gem XT350 was a popular RTW steed (not many left now).
Personally I recommend at least 600cc because it has the power to get you and your luggage out of heavy mud. My own preference is to stay well away from anything over 700cc as these things are super expensive to buy, thirsty, bloated and way too heavy. Forget a huge lumbering beasts like the mega-popular BMW 1200GS they are best used for tarmac touring.
All these bikes above are considered suitable for hard-core RTW travel.
There are many other options and hopefully others will see this thread and give their valued advice....
If you really want to use something small then the Honda C90 step-thru makes ultimate sense. Cheap to buy and run. dependable engine, everyone has repaired one, easy to find parts and it's got a RTW pedigree second to none. But be prepared to do it very slowly and to have a sore back side every day.
I wish you well.