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“When I did my trip to Alaska a few years ago, most of the gas I could buy at some point was 87 octane”. When I went to Alaska I just was glad they had gas at fuel stops and it didn’t matter what octane. Low octane is better than pushing👍🏻👍🏻.
I remember buying 85 in the Midwest on the way back to Texas and didn’t have any ill effect other than generating forward motion.
Octane in pump gas is obtained by a small amount of additive.
msking it short, Yes, a motor that was designed to run on 91 will run on 87. But, not as well. The knock detection system will retard spark and turning, to reduce knock , and thereby Reduce power. Modern Harleys are tuned to maximize hp and torque from a somewhat primitive design. Go ahead...run yours on 87 if you are happy with it. But, leave it for me, and actually I wish I had access to 92 or even 93. Because I know my bike likes those better than 91.
Trade off here 91 Octane is most ethanol free 93 is 10% blend. So a toss up if you want Non ethanol the 91 is it and if you want 93 you get the blend.. Except for a slight drop in MPG I have never had any issues running either.
Back many years ago I was told a small amount of K1 in the gas would raise octane. But how much would be a big question. Gave up long ago worry much about it pull in for gas get what they have.
I have used this stuff along with 91 octane fuel in my bikes and have had good results especially two up on my ultra!! and as a added bonus the fuel stabilizer in it
I'm using 100 octane. But not in my 2017 Street Glide. Afaik the sensor in this bikes doesn't recognize fuel higher than 98. I use it in my 92 Electra Glide, where the high octane is a "reserve" for bad conditions like heat or a not 100% perfect working ignition. Does it work? I don't know - but I hear no knocking and it feels like I give a special care for my loved old bike
I'm using 100 octane. But not in my 2017 Street Glide. Afaik the sensor in this bikes doesn't recognize fuel higher than 98. I use it in my 92 Electra Glide, where the high octane is a "reserve" for bad conditions like heat or a not 100% perfect working ignition. Does it work? I don't know - but I hear no knocking and it feels like I give a special care for my loved old bike
Just an FYI. To give a general number (it depends on actual engine design and I am simplifying it) optimal maximum combustion pressure point is approximately 15+- degrees ATDC. This is where you really want the expansion of the burn to be pushing down on the piston.When you run race fuels, they require more pressure and heat to continue burning once ignited. If the motor does not have the increased compression to required to help the fuel burn as intended, the sweet spot is missed and the burn is still expanding past where maximum pressure should have been. The result is a loss of power but it does smell good LOL.
Last edited by Ed Ramberger; Jan 31, 2021 at 09:20 AM.
Ok...here ya go. Exactly what I was saying. Todays perform ce vehicles will try to get the most performance until it knocks , and then back off until the knock stops. So, running a higher octane will ALLOW the motor control circuitry to develop as much power as it can. Of course within the limits of the design, Lower octane will not allow the motor to develop as much power. Read the fine print in this ad. If premium fuel is not used, performance will decrease.
Last edited by TriGeezer; Jan 31, 2021 at 03:22 PM.
you can tell there's a snow storm when I'm on a octane thread...........91 + with stabil for the winter month's......as for why? flash point is higher on high octane fuel .....high compression cyclinders act like diesel engines (to a point) when operating...Compression + pressure equals heat....no spark needed.....using a fuel that requires a spark under those conditions is paramount for proper engine function and less stress to the components 87 octane has a lower flash point making it more prone to dieseling or engine knock....in severe cases you shut the motor off and it would still sputter and run as it were...all thou not very well.......So put the good stuff in it at every fill up and light up when your in the wind....now there is a challenge!!
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