They are pretty much universal amongst the Yamaha's I'd think. Clamp one end to the stem and the other to the frame and VIOLA!!! The only real difference between brands is the size of the clamps. Example: the Yamaha frame might be 7/8" OD and the Honda's are 1" OD, or the old 250R's used a square tube frame, so it req'd a diff. clamp. Those sizes are probably incorrect, just for example. There's really not much difference between a "Brand X" Honda stabilizer and a "Brand X" Yamaha stabilizer as far as performance goes.
God must love stupid people; He made so many.