Up until last week I was using only unleaded 91 octane Premium (10% ethanol). Then I had a brainstorm. I usually pump 3.5 gals per fill-up. If figured, of that, at least a 1/2 gallon of it (left over in the common hose) was whatever grade the last person filled with (usually 87 regular). I switched over to using 87 (which, btw, the owner's manual recommends on a V-Star). I have not seen or felt any difference in performance, other then "perhaps" having to keep the choke open for 15 or 20 secs longer when starting a cold engine.
I had the carbs rejetted when 91 octane was in the tank.
If I plan to continue to use 87 Octane, do you think I need to adjust the needle settings?
2007-05-20 13:32:52 · 10 answers · asked by V-Starion 5 in Cars & Transportation ➔ Motorcycles
No, if it works don't fix it. I have to use high octane because of the high compression engine, sux right now with the price of fuel, but my motor is not stock, it's got 11:1 compression and have to tap the starter to get it off the compression stroke so it will turn over, so if your owners manual says you can use 87 be happy and enjoy, if I try it my harley sounds like a soup can full of rocks it pings so much. Have a good day.
2007-05-20 13:45:44 · answer #1 · answered by Anonymous · 2⤊ 1⤋
This is something for you to think about, and may explain a thing or two about fuel.
A bike, car, or any other engine will make the most power with the lowest octane fuel it will run with at full load, without distress. This requires optimal ignition timing and mixture, The lower the octane, the faster the burn, If mixture and advance are not correct, or compression is too high, you get detonation, which is the remaining mixture in the chamber explodes. Bad news. Modern engines are, for the most part, well designed, to run quite high compression ratios, and not have places in the chamber which invite detonation. So, if your mixture and advance are spot on, and the bike does not detonate, or overheat, going to a higher octane fuel will not increase power. And nothing says that if a bike is spot on for regular gas, that it can be switched to high test and make more power. Remember, each engine design has its optimal ignition advance point, Best power comes with the fuel which fits this point. With sport bikes, 11:1 or so compression ratio, 91 or so octane is needed. If you have 9:1 or so compression, normally 86 octane or so is good. Remember, this is for 4 valve, center plug engines only. A Harley, and other 2 valve engines are a different story.
Cheers,
Tomcotexas.
2007-05-20 22:54:33 · answer #2 · answered by tomcotexas 4 · 1⤊ 0⤋
You should stick with what your manual recommends - your bike will not run any better on 91 octane than 87, even with a rejetting. You bike will probably acutally run a little better on the 87. The guts of the engine, primarily compression, are the basis of what octane level you should use. Use the lowest level recommended, or you are just wasting your money.
2007-05-20 20:53:11 · answer #3 · answered by CafeTBird 4 · 2⤊ 0⤋
I run 91 or 93. 91 minimum, as called for in the owner's manual.
I run 87 in my lawn mower, as called for in the owner's manual.
Aside from the manuals and lables, these choices are based on other things as well. Personal preferences based on experience with different engines and other truths. Some have been listed here by others.
You are best off running what your engine was designed for (87) unless you make changes to the engine itself.
2007-05-21 16:38:09 · answer #4 · answered by Firecracker . 7 · 0⤊ 0⤋
About the settings I have no clue. But, just keep using 87 octane since you didn't feel a diff. I too did not feel any diff at all so I'm sticking with 87 vs 93.
2007-05-21 10:47:20 · answer #5 · answered by jesse w 2 · 0⤊ 0⤋
The rule of thumb is that higher compression engines want higher octane.
My 121" on my FXR is a 10 1/2 :1 compression, on a few occasions I have been forced to run 87 or 89 and the bike did "ping" . I also have a Mustang Cobra with a SVT package ,Premium only or it "pings" under load.
If you want to run lower octane you don't have to re-jet ,but rather retard your timing a bit as this will reduce the compression before firing.
2007-05-21 01:58:40 · answer #6 · answered by Anonymous · 1⤊ 1⤋
I shouldn't be answering this cuz my bike is fuel-injected. But there is a station near my house that sells 91 octane "un-oxygenated". There is NO ethanol. It is 100% clear gas. (it is as clear as water) My bike runs awsome when I use this. If you can find it...USE IT!
It is the only fuel that gets pumped through its particular hose, so that is all I'm getting.
2007-05-20 20:40:43 · answer #7 · answered by Dudeman 3 · 2⤊ 0⤋
My owner's manual calls for high octane quality fuel. I avoid stations that use a single hose to pump all grades.
2007-05-21 18:08:11 · answer #8 · answered by Frank R 1 · 0⤊ 0⤋
i found that anything higher than 87 just blues my pipes faster, does nothing performance wise.
2007-05-21 03:41:41 · answer #9 · answered by Anonymous · 0⤊ 0⤋
if you havent felt any difference then why bother ? just run it and be happy
2007-05-20 21:06:07 · answer #10 · answered by wonderboy n 5 · 0⤊ 0⤋