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RE: Tried a lower octane on my F2

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RE: Tried a lower octane on my F2 - 10/17/2006 5:03:56 PM

N8 Dawg

Posts: 1737
Joined: 7/18/2006
From: Middletown OH
Status: offline

Well I ran 87 in my bike and now it fires right up when the choke is on, before it would not, and I would have to keep giving it a little bit of gas until it would run good....now it fires right up and actually does run better??? Dunno why 93 made it run like that, I would have thought it would run better???

(in reply to shiphteey)

Post #: 16

RE: Tried a lower octane on my F2 - 10/17/2006 5:21:15 PM

jaboyak

Posts: 54
Joined: 1/29/2006
Status: offline

Common misconception: High octane equals more power.

Completely untrue in every sense of the word.

Octane is SIMPLY resistance to detonation. So, the lower the octane, the more fuel that burns.

(in reply to N8 Dawg)

Post #: 17

RE: Tried a lower octane on my F2 - 10/17/2006 6:20:49 PM

N8 Dawg

Posts: 1737
Joined: 7/18/2006
From: Middletown OH
Status: offline

I figuered our bikes ran on premium fuel, i dont have an owners manual so I dont know what it calls for. My formula runs on premium, and if you put 87 in then it runs like

and it will ping......

(in reply to jaboyak)

Post #: 18

RE: Tried a lower octane on my F2 - 10/18/2006 11:31:48 AM

drifterjerry

Posts: 13
Joined: 9/7/2006
Status: offline

just to throw a wrench, anyone notice any performance differences when using the fuel that has the 10% ethanol? in NC a few pump stations i have gone to have the sticker that say the ethanol percentage. i am not a big fan of it b/c it throws my AFR off on my nissan, but thats a different story.

this thread has me wanting to try the lower octane imediately on my 40K (no rebuild) F2. think i will just try the 89 first.

(in reply to N8 Dawg)

Post #: 19

RE: Tried a lower octane on my F2 - 10/18/2006 12:00:22 PM

Tahoe SC

Posts: 5874
Joined: 8/24/2005
Status: offline

my 40K f4i still runs on 87, no pinging or anything...
since it's an old motor, there's always chance of build up and what not...if so, it could make you ping at 87, then just go up. but the point is to use the least amount of octane fuel possible without predetonation.

(in reply to drifterjerry)

Post #: 20

RE: Tried a lower octane on my F2 - 10/19/2006 10:00:55 AM

jbreit

Posts: 306
Joined: 10/13/2006
Status: offline

Taking the "resitance to detonation" definition a little further...the higher the octane, the more energy it takes to make the fuel combust.

In the cylinder you have pressure, heat and a spark...all of those energy sources combine to ignite the fuel. If that level of energy isn't high enough, it won't fully combust (it also affects the speed adn timing of the entire combustion process but thats getting beyond the scope of this). So, thats how you can get more power out of lower octane....you are actually running "lean" on higher octane. So the top speed question...sure....your bike is short on power and can't top out. You've got a flat spot in the power band...sure...it explains all those things.

Something else to pay attention too. Some manufactures spec octane in RON number....most fuel is sold on an (R+M)/2 octane rating...the (r+m)/2 rating is higher than just the RON. So if your bike specs RON of 89, you can run an 87 (R+M)/2 fuel in it. The F2/3 is fine to run 87 in....but, some bikes do need 91 these days....my 2001 zx6r for example.

Ethanol will lean you out as well....and hence cost you power. Ethanol has a higher octane rating than gasoline alone. I avoid ethanol and oxiginated fuels when I can.....its politics medling with things that they don't understand. Currently Shell gas is about the last one without ethanol around here....next year I believe that will end too. Being a Mechanical Engineer that worked in engine research for two years in college, I giggle at some of the propaganda I read and hear.

Playing around with different fuels like this can give you clues on your carburetor tuning as well...you put in a 10% ethanol and that mid-rpm stumble goes away...you must be rich there...and so on.

John

(in reply to jaboyak)

Post #: 21

RE: Tried a lower octane on my F2 - 10/19/2006 1:44:05 PM

JJHUNSECKER

Posts: 33
Joined: 7/19/2006
Status: offline

WOW. I'm trying 89 or 87. Thanks guys. Never would've occured to me, I always run 91. Interesting.

(in reply to jbreit)

Post #: 22

RE: Tried a lower octane on my F2 - 10/19/2006 2:26:01 PM

pbbreath

Posts: 52
Joined: 10/17/2006
Status: offline

Tried 89 ( I also only will run Shell ) Cant say that I noticed a reasonable difference. Honestly with my knowlege of cars a bike that is running over 11:1 compression ratio should be run on 91+. I live in Redding Far northern California and in the summer its often close to 120 here so 89 wouldnt even be an option. I do understand your arguments but its gonna cost you a few cents to fill with premium and it might gain you 1hp to run regular when its not over 90* outside. Id rather run on the side of safe and never think that my bike is going to ping.

Just my $0.02.

Morgan...

(in reply to ep03TN)

Post #: 23

RE: Tried a lower octane on my F2 - 10/19/2006 11:38:46 PM

superstunter

Posts: 16
Joined: 10/16/2006
Status: offline

Today I flled up with 87 and its the same feel. I have always ran 91 or 93, and I have a D&D slip on and a K&N filter. I think its about the same feel, just less money!

(in reply to pbbreath)

Post #: 24

RE: Tried a lower octane on my F2 - 10/19/2006 11:40:56 PM

Ar15 guy

Posts: 312
Joined: 9/30/2006
Status: offline

I just got my bike running....

I will admit I used 87 octane from my lawn mowers gas can. (It is fresh tho)

It runs fine on it. No pinging or anything. I do have a small exhaust leak at the head tho. I need some new gaskets. Bike runs very well. I was suprised.

(in reply to pbbreath)

Post #: 25