Not talking about northern areas but how easy it is on a bike for Khi-Lhr-Khi, can one go non stop or a stay at Sadiqabad or RYK is must.
Also why only 125 or 150cc 4stroke is been considered here, any well maintained 2s or 4s bike can do that even there shouldn't have any problem with a good condition Honda or Chinese 70 IMO.