I have been running high test in mine since I bought it but then again I have used the highest octane available in all the bikes that I have owned. I noticed one of the guys I ride with putting regular in his RKC so I thought this would be a great topic for a poll.

 

premium 93 octane. Usually shell.

 

I pretty much stick with gasoline most of the time..........

 

highest octane i can get... try to use shell as well

 

Manual calls for 92 octane, it is what I run.

Shell/Chevron and they are high volume stations.

 

I can't run anything less than 91 or I get pinging. Even with the higher grades on long trips I will get slight pinging on 91. I usually stick to Marathon, Shell or Sunoco fuels and have good luck with them.

 

High test when temps are over 90.
Mid range fuel when temps less than 90

Running 10.5 compression, a little higher than stock.
No pinging issues whatsoever and I would doubt, that if tuned properly the relatively low-compression stock aircooled Harleys would have any problems running on mid grade fuels even when over 100 degrees outside.

 

highest I can get

what's the difference between mid-grade and high? $.10/gallon? For a 5 gallon tank... do the math and use high test.

 

Always 92. I'm with Bry, don't see any reason to run anything less!

 

I know this is against what the owner's manual says....but I run the 87. I tried the higher stuff and it really made my bike "rattle" and sound horrible. My riding buddy only uses the 91 and he said he gets the opposite result than me (says his bike really "pings" with the 87). I even tried alternating tanks with the good stuff..........result was the same. I'm sticking with the 87.