Please post a link to that recommendation?

I believe it says Premium of 91 or better or something to that effect.

As others have mentioned, there are lots of places where 91 is as high as your going to find.
And the bikes run just fine on it.

Here in Missouri, it seems to be hit or miss on finding 93.
Some have it, but quite a few only have 91.

 

I have run 87 octane from day one and have never, I repeat never had any pinging. That is on all 14 of my HD's from the TC88, TC96, TC103, TC103HO and TC110 motors. No problem on the 4 EVO2 1200's either.

Legal fact: The government requires that all motor vehicles sold in the US be able to run on 87 octane.

I did the same on my Corvettes and Viper.

Just don't lug the motor and treat the fuel to remove carbon every 3,000 miles.

I used to do that by removing the AC and misting with water. Now I just add Enron's Techron which does the trick.

If the bike didn't come with an oil cooler I would add one. The other thing is to run a power AFR. 12.5 to 1 yields the coolest incoming charge to cool the valve, cylinder walls and piston top. Heat is the principle cause of pinging. The emissions compliant 14.6 to 1 runs the engine hot.

Please take note that 91 or better is specifically worded "RECOMMENDATION" by HD and not "REQUIRED" because they legally can not do that.

 

91 or better.