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Discussion Starter · #1 ·
I recently returned from a 2500 mile ride on my 1991 FXSTS . I started using top grade gasoline, but out in the boonies at times all I found was regular grade. I had been recording millage on each fill up. When it stayed the same I paid attention to the power ,and for my touring style of riding nothing changed with the grades of gas, no pinging or anything . . Except I now have more money to spend by b buying the cheap grade My bike has a stock Keihin carb and engine .
Has anyone noticed the same thing ? .
 

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I switched from 93 hi test to 89 midgrade in my Ultra CVO and see no change what so ever - except more money in my pocket as you mentioned.
 

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2004 Ultra Classic
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Hell might as well go to the Speedway and put some corn fuel in there save some more. o_O
 

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1997 Softail Custom (FXSTC)
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A stock Evo (big twin, not Sportster) was designed to run on 87 octane. It won't run better on higher grades of fuel, the only advantage to running 91/93 is that it has higher levels of detergent, but it won't make better power or fuel economy. Quality of fuel is a separate thing... shit gas is shit gas regardless of how high its octane is. It'll run better on 87 octane Shell, Exxon, BP, 76 or whatever top tier detergent fuel brand than it will on 93 octane from a no-name garbage gas station (though not all unbranded gas stations are crap).

Octane rating is strictly the fuel's resistance to spontaneous ignition under heat and pressure (detonation). Has nothing to do with power or efficiency in and of itself.

The only time you see an increase in fuel economy or power by running 93, is some fuel injected cars are designed in such a way that the computer detects what gas is in it and changes the engine's tuning accordingly. Otherwise a vehicle that doesn't have a computer designed to do that will run the same no matter what grade you put in, so long as it's the minimum octane rating or better.
 

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Hell might as well go to the Speedway and put some corn fuel in there save some more. o_O
Speedway, Racetrack and Murphy's - my go to places. They are convenient to me.
 

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Gasoline grade and quality all depends on what part of our great country you buy that fuel at !

That being said, What bar do you buy your shot of whisky at ? Is it the same in Washington St. as it is in Washington D.C. ? I'll wager the gas in those two locations aren't the same, but I sure think the whisky would be. WHY ? Because whisky is more regulated than gasoline !
The gas engine vehicles we have been operating for the past 100 years or so in America have been functioning on everything from diesel to corn licker' and pure alcohol and stipend with pee at times !

In the past 40+ years I've been wrenching on motorcycles and other vehicles the only time I've encountered a fuel problem is when the fuel was found to be contaminated or of obstructed flow. The most common problem is fuel that contains to much water. That water accumulates inside the 500 gal. tanks at the fill station when they drain down and condensation accumulates inside the tanks prior to when they get refilled. Those tanks have water filters but ain't 100% perfect.

So back to the OP's thread about gas quality at the pump. I'm more confident in the shot of whiskey I get at bars across America than the quality of gas from the pumps I get across our great country !

Damn long post considering !
 

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You should be fine especially if you know the engine is stock or at least the compression hasn't been raised much. Just as a check you can pull your spark plugs and take a look. You don't want to see any shiny bits/flakes on your plugs. As long as the plugs look good and you don't actually hear detonation keep the extra money in your pocket.
 

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Discussion Starter · #10 ·
I was just reading my 1991/1992 Softail service manual, it to use gas of 87 octane or higher . Looks like That's the way to go on these carbed bikes . I also read to avoid ethanol which can cause the fuel lines to deteriate .
 

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1997 Softail Custom (FXSTC)
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I was just reading my 1991/1992 Softail service manual, it to use gas of 87 octane or higher . Looks like That's the way to go on these carbed bikes . I also read to avoid ethanol which can cause the fuel lines to deteriate .
That's really only an issue if it sits a long time.

Modern fuel lines can handle it. I run 10% ethanol in my 97 with no problems. The owner's manual (at least for mine) indicates it's fine to use up to 10% ethanol blended gas (but not more).

Ethanol in gas has been a thing in the US since the 80's. Unless you got a bike designed to run on leaded gasoline, 10% ethanol isn't going to hurt anything (as long as you don't let it sit up forever).
 
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2011 Harley-Davidson FLHX Street Glide (Ginger); 1992 FXSTC Softail (Stitch)
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I recently returned from a 2500 mile ride on my 1991 FXSTS . I started using top grade gasoline, but out in the boonies at times all I found was regular grade. I had been recording millage on each fill up. When it stayed the same I paid attention to the power ,and for my touring style of riding nothing changed with the grades of gas, no pinging or anything . . Except I now have more money to spend by b buying the cheap grade My bike has a stock Keihin carb and engine .
Has anyone noticed the same thing ? .
FWIW, the owners manual of my 1992 FXSTC says that it was designed to run on 87 octane gasoline with up to 10% ethanol.
 
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