This bike of yours reminds me of my father's 1979 modle yb , it had number gaa 8o84, one tough ***** it was , dad sold it with a heavy heart , my dad has kept 79 82 and 89, i my self have owned 87 88 89 and 91 with time but my 89 is my favorite , its on sleve sadly but carb gear clutch coils coil plates are orgnl body is painted and messed up as i dnt care of it now but the thing is that yamaha is a bike worth keeping