87 VS 91 OCTANE... NOTICE ANY DIFFERENCE ??

higher octane gas is designed for high compression engines these are low compression engines you'll have to change out the pistons to high compression pistons and retime the engine to see any gains. Higher octane doesn't mean your getting more power it means it has a higher ignition temp which is what high compression engines need. It takes more heat to ignite 93 then it does 87. If you run 93 in these bikes your actually losing more hp then you would with 87. I haven't run 89 in my bike yet and haven't looked to see what the optimal octane level should be it is most likely 87 but could be 89. I know its not 93. the reason higher octane is more expensive is because it is not produced as much as 87 not because it is a better fuel. Hope this helps

OUCH 87 here is $3.41 and 20 cents more for 93

I'd run 85 I'm not a expert with the elevation effect but less air and lower ignition temp makes since