I use to run Valvoline or Castrol GTX 20W50 in my older Yamaha singles. It worked fine, but they were a bit older and bigger in capacity.
Now days, with that bike, I would be reaching for a mineral 15W40 HDEO like Delvac, Delo, Rotella.
There are both full and semi-synthetic HDEO options too, but I really like the Delo 15W40 as a bike oil. Mate is running it in his 600cc Honda single right now. He likes it best of all the oils he has tried so far, shear resistant and low consumption.
Enjoy your Yamaha single - great bikes !!