I know it's not a 250 but I had to share. Came across this mad bugger in Albany WA a couple of days ago. He is riding his Czechoslovakian Jawa 350 (with Czech rego plates) around Australia. Drum brakes, rust in frame and exhaust pipes, bad oil leaks and a pair of tyre irons taped to the front of the frame but he looked like he was having a great time Don't know if it is an actual model but the tank had 'Jawa Dingo' labels on it.
Interesting story. He is a cancer survivor and travelling the world on old Jawa's. Any money he makes goes to the Pilsen oncology. He is doing a figure 8 lap of Oz and also a lap of Tassie, all in 90 days on his own with no GPS, no drones and no satelite phone (he likes the quiet). He is retracing some of the route taken by a Jawa 250 in 1974 across the Nullarbor. His bike is a 1986 Jawa 350cc two stroke twin. Modified large tank (26Lt), strengthened rear axel and frame, modified electrics, painted to match outback dust and called a 'Dingo' for the ride around Aus. More here. http://jawakolemsveta.cz/jawa-kolem-sveta-i/trasa