I appreciate everyone's help. But here is the bottom line. I dont know about specific gravity, humidity, and all that other stuff. If I have to consider all that in order to save 80 cents per fill, screw it I'm at 93
I've run my bike for over 10,000 miles with 93 octane and it purs like a kitten. I run my bike HARD, I beat the crying sh*t out it, I launch hard, I redline it constantly, I brake hard, I ride this bike how it's supposed to be run.
This is my second tank of 87 octane. The first tank ran fine, but then again it was probably half 93, half 87. I filled it up again with 87 octane, and this is when the problem started.
I was riding, i could hear the engine pinging and knocking under the gas tank. Sounded like I was dragging a soda can behind the bike. The problem showed up only under hard acceleration and high RPMS, once I hit about 50% throttle or went above 6000rpms, the sound was VERY noticible
I filled it back up with 93 octane, and it runs perfect, no noise, no pinging or knocking, just smooth quiet power.
I'm not trying to start a whole 87 vs 93 octane debate with petroleum engineers. I'm just simply saying in my bone stock, 2002 Black hayabusa, 87 octane made the bike run like sh*t run over twice
I'll never put 87 octane in my bike again, 93 from this point forward
Mike