Fuel Question
Seasoned HDF Member
Joined: May 2012
Posts: 32,934
Likes: 36,031
From: Carlsbad, CA
Appreciate the input. I run efree in my small engines ( Polaris atv, weed eater, generator) but premium in my sports car and road king. I was asking because my riding Buddy ( and expert) was recommending I switch. 89 efree is readily available here, and I could add octane booster but....
Elite HDF Member
Joined: Mar 2014
Posts: 4,214
Likes: 661
From: Prior Lake, MN
You wouldn't get more power with higher octane because there is no additional power in that fuel to be had. If your bike runs fine on the 93, then anything beyond that is a waste of money. If it pings on 93, something is amiss.
Stellar HDF Member
Joined: Jan 2007
Posts: 2,627
Likes: 1,348
From:
Those saying that there is less power with higher octane are correct. High octane is more resistant to combustion - which is why it's used in high compression and other engines likely to experience pre-detonation. Piston powered aircraft use 100 octane fuel (with lead) not for added performance but because it's easier on the engine. Most piston powered aircraft are designed to only make about one horsepower per two cubic inches of displacement and run modest compression ratios. Use what is recommended in your motorcycle.
Me? If the engine is fuel injected, has an ECM with a knock sensor that adjusts ignition timing, injector timing and the like ... then I run 87 octane; always have and never had a problem.
Me? If the engine is fuel injected, has an ECM with a knock sensor that adjusts ignition timing, injector timing and the like ... then I run 87 octane; always have and never had a problem.
Grand HDF Member
Joined: Jan 2012
Posts: 4,458
Likes: 2,877
From: Oklahoma
Octane is another way to classify flash point. Compression creates heat, that is how a diesel works. About 22:1 compression ratio creates enough heat to ignite diesel fuel. Higher compression engines create more heat during compression. If the fuel octane is too low, the fuel will spontaneously ignite before the spark plug makes the spark. It ignites all at once and that makes the knocking, pinging we hear. Higher octane fuel has a higher flash point so the heat made during compression is not enough to make it light spontaneously, it "waits" for the spark. Octane is NOT an indicator of quality. If you are interested in the best fuel quality, consider going to "toptiergas.com" and read about the additive packages and see the list of top tier brands. Those who live in or near the Rockies will find their stations sell fuel that is a lower octane than the standard 87/89/91 available in the low country. The higher you go, the less dense the air is. When an engine sucks in less air, there is less heat created during compression so lower octane fuel works fine at higher altitudes. This is for normally aspirated engines. Add a turbo or super charger that can compensate for the altitude and the higher octane is needed even at higher altitudes.
Road Master
Joined: Jul 2010
Posts: 798
Likes: 168
From: Tryon, NC Cape Vincent NY
I know the Motor Company says to use hi-test in my bike, I normally use Ethanol Free 90 Octane, but due to the gas shortage, I can only use 87.
I haven't experienced any issues at this point in time, but I am also shifting at a higher RPM , running a gear lower, and trying not to lug the engine.
Hopefully they will start selling hi-test this week.
I haven't experienced any issues at this point in time, but I am also shifting at a higher RPM , running a gear lower, and trying not to lug the engine.
Hopefully they will start selling hi-test this week.
Stellar HDF Member
Joined: Nov 2005
Posts: 3,183
Likes: 836
From: KMHT KFMY
@TriGeezerwe need to find the OP and see if 11 years later his engine held together the last time he logged in was 9/13/3013.... if it was pre-detonating it surely would have gone thru a set of connecting rod bearings and possibly pistons by now
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Seasoned HDF Member
Joined: May 2008
Posts: 21,143
Likes: 12,707
From: South Carolina
No such thing as pre-detonation...
Low octane fuel can allow an engine to Detonate, which means the fuel ignites somewhere in the combustion chamber away from the spark plug.
Detonation occurs after the spark plug fires.
This is what we hear as a ping.
Preignition is when there is a hot spot somewhere in the combustion chamber, and the fuel ignites before the spark plug fires.
https://www.faasafety.gov/files/noti...reignition.pdf
Low octane fuel can allow an engine to Detonate, which means the fuel ignites somewhere in the combustion chamber away from the spark plug.
Detonation occurs after the spark plug fires.
This is what we hear as a ping.
Preignition is when there is a hot spot somewhere in the combustion chamber, and the fuel ignites before the spark plug fires.
https://www.faasafety.gov/files/noti...reignition.pdf
Last edited by Dan89FLSTC; May 16, 2021 at 10:16 AM.
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