And this is the first model for the full 350 cc bike, not very beautiful, to say the least. The engine is now clearly the YR1 with normal induction. This type of airfilter was kept for the YR1 but covered by the sidepanels.

Yamaha prototype YR1

The frontfork comes completely from the YDS3C Scrambler. it shows that the Engineers were "clobbering" things together just to see what looked best!