87 is your fuel. Technically the bike should run fine on 85 but not that e85 crap. That will probably destroy your engine. So stick to 87. It's a safe number you won't confuse.
The info plate on the right side of my frame (by side cover) states to use 91 octane min. I will not put alcohol contained gas in my bike or any of my small engines. I think the non-oxy I buy is 91. If they sold it in 87 I'd try it. I do much with old outboards and that alcohol stuff raises holy hell with the carbs and the tanks get nasty too. Probably from the extended non-use. For me it is simply not worth using.