The TR1 was produced 1981-1984 (ca) and mainly sold in Sweden and Germany. It has a 1000 cc engine, producing 70 bhp, wich is basicly the same engine as the 920 and 750 models except for the cylinders of course! It features an enclosed caindrive (same as the 920R i think).  You can see photos at the link "Galleri" at this site!
Yamaha has a new model they call Bulldog wich has its origins in the TR1 model. It has a 1100 cc engine (64 bhp i think), aircooled and of the same type as TR1. Tubular frame, backweeldrive via cardan.