Yamaha bikes are so far good for Nepali roads as it got good handling akin racing bikes which can twist and turn in any situations but riding in Nepal is gripping than soothing.You got to be careful every sec.,if you are an Xpress rider.You won't need a heavy engine,expensive ride as there are not too many open lanes for you to zooooom and the roads are full of vehicles which you got to share with,viz: buses,trucks,trippers(Road Kings),micros,tempos,mini-buses,mini-vans,bikes,taxis,private cars,tractors,cycles......cattle,pets,pedestrians,traffic police,which can bring about a sudden halt instantly--anywhere.

Driving/riding in Nepal is more like a compromising game than a systematic one( reminds me of Trinity riding a Ducati in Matrix).Having good communications with surrounding vehicles with proper light indications and a greeting honk can save a lot of hazards and speed.The gas aka petrol is as precious as pearl and getting it comfortably is like a full moon event so choosing any bike less that 250 cc can save you a lot of time and currency.As there are no Inter-states in Nepal...you ought to have a keen eyes to watch every pot holes and every child that's crossing the roads and some other arrogant drivers who are always late, therefore dangerous.Riding in early mornings and at night can bring a lot of joy with open roads minus people,when you are really aligned with your bike.Rest than that...its all skills...have a great trip.