Himalayan Motorcycle Touring - Anyone done it?

I am a westerner considering taking a motorcycle tour into the Himalayas next summer. I would like to ride to Ladakh, India - the highest navigable road in the world on an organized tour on my Royal Enfield. My main problem is I cant stand curry or most Indian food! On the other hand there are some fantastic Thailand/Laos/Burma tours available that look similarly spectacular. Can anyone who has been on such a tour tell me what the travelling conditions were? How did you stomach hold up? I would hate to get the runs at 18,400ft!