Anyone interested in a well put together rundown of various Royal Enfield diesel builds and options would do well to check out Dieselbike.net's
Royal Enfield Diesel Motorcycles website. There's some lovely stuff there.
I'm led to understand from these Forums that there are very few diesels here in the USA, but the German-language Royal Enfield Forum over at
www.royal-enfield-forum.de has several owners with such beasts, and they're usually discussed under the
"Dieselmotoren" Subsection of their "Royal Enfield pre-unit" area. (Registration and login required for access). Obviously the main language of discussion over there is in German, and it's often a highly colloquial, slangy and obtuse (almost code-like) German at that, which would surely confound
Google Translate, but occasionally you do see the odd bits of English. They really know their stuff though, and, like here, they're super friendly. I'll give 'em that. If I had questions about an ailing diesel Enfield, that's where I'd turn.