IIRC, "UJM" is a acronym from the 90's describing the current run of Japanese four cylinder motorcycles that you could make to look like anything. If I'm not mistaken, a motorcycle mag started the use of the term. Does it actually apply to the earlier models from the 70's and 80's? Maybe, maybe not.
IMHO, I think not. But,,,,, I see the term being used everyday in the motorcycle world now to date back before the "Big Four" started making inline fours. Here, other forums, and on the street.
Just an observation from a 42 year old who started riding on a new 1969 Honda Mini Trail 50 in 1970. It was definately NOT a sportbike, but remains to this day, in my mind, one of the two most fun motorcycles I have ever ridden. The other is my 99 ZRX1100. The other 40-plus motorcycles, dirt and street, and atv's were fun to an extent, but not like my first and my current.
Sorry for the hijack.