Run premium fuel?

EskimoPie

Supercharged
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Dec 1, 2020
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295
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Sahuarita, AZ
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2021 Rocket 3 GT
I've always used premium (91 R+M/2 in Arizona) and been happy with the performance over the past 7k miles. Just idly flipping through the manual though and I noticed it only calls for 87 knock index fuel. When I purchased, my service manager was adamant to use premium fuel. Does anybody run regular grade fuel? Any issues with it?
 

DOCGSS

.020 Over
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Jan 28, 2021
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22
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Rocket 3, HD CVO SG, Triumph Bobber
I run premium. The higher octane provides protection from pre-detonation, and quality brand premium fuels have more and better detergents to clean fuel injectors and help prevent carbon buildup on valves and pitons. What premium fuel does not provide is more power, that is a common misconception.
 

EskimoPie

Supercharged
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Dec 1, 2020
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295
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Sahuarita, AZ
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2021 Rocket 3 GT
I run premium. The higher octane provides protection from pre-detonation, and quality brand premium fuels have more and better detergents to clean fuel injectors and help prevent carbon buildup on valves and pitons. What premium fuel does not provide is more power, that is a common misconception.
Quality brands and additional detergents are unrelated to the octane choice as the Top Tier designation requires the detergents to be added to all grades.

While higher octane prevents detonation in high compression engines that are designed for it, in engines that are not designed for it, you don't get that benefit as you won't be getting detonation even with lower octane.

Hence the question... if our motors are designed for 87, why run premium? Does anybody here run regular consistently? Has anybody experienced knocking with 87 octane?
 

TURBO200R4

stand up straight and grab the world by the a$$
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Jan 24, 2013
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TUCSON AZ
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07 rocket III classic
Quality brands and additional detergents are unrelated to the octane choice as the Top Tier designation requires the detergents to be added to all grades.

While higher octane prevents detonation in high compression engines that are designed for it, in engines that are not designed for it, you don't get that benefit as you won't be getting detonation even with lower octane.

Hence the question... if our motors are designed for 87, why run premium? Does anybody here run regular consistently? Has anybody experienced knocking with 87 octane?

check your manual i think the new rockets require premium
 

EskimoPie

Supercharged
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Dec 1, 2020
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check your manual i think the new rockets require premium
Nope:
1630456974650.png
 

leatal

Turbocharged
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Mar 11, 2015
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781
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Dothan, Alabama
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2014 Roadster, 2020 Rocket GT
My Owner's Manual doesn't have the second paragraph but the specification pages say minimum octane of 95 RON which is 91 minimum in US. I also only use Shell premium (if possible) as it has the most cleaning detergents of all top tire fuels. Plus if you join the fuel rewards program, you save 5-10 cents per gallon.
 
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