Thoughts on fuel...

I always run 93 octane (higher if I can find it). Today I found a gas station near me that has an ethanol free pump, but it is 89. Kinda started thinking while I was riding is sacrificing octane worth the absence of E. Kinda thinking it is, but I have no real basis for that thinking.

Any thoughts?

What about different bikes/motors. I have a HD, Buell and single cylinder dual sport.

91 works good for me.

To try to keep this as short as possible...

Higher octane fuel is not "better". You should always run the lowest octane possible in an engine without causing detonation/pinging. Running higher octane than needed is not only a waste of money but promotes carbon buildup(gunk).

As far as ethanol free, that is a HUGE plus IMO. Not only does straight gasoline have more energy per volume as compared to ethanol which results in more power and mpg, it is also not harsh on rubber gaskets, hoses, etc. and also lasts longer and does not "suck" in water.

Straight 89 fuel is not technically high enough octane for the buell though, as it requires 91 octane or higher. There is no "cross reference" between octane and type of fuel. Octane rating is octane rating, whether it be ethanol blend or straight gasoline.

FYI, octane rating is the resistance to detonation, higher rating gives more resistance. Higher compression and more timing advance require higher octane rating(slower burn).

All that said, you may be able to get away with 89 octane on your buell if you have some of the following: Breather reroute(because oil vapor in the combustion chamber lowers the octane rating of the mix), colder heat range spark plugs(colder plugs are less prone to detonation), higher elevation(higher elevation is less prone to detonation). Also, a colder engine running temperature makes the engine less prone to detonation, but that's hard to accomplish on an air cooled buell.

I, for example, run a 93 octane tune on my truck, but use 91 ethanol free fuel. I use a colder thermostat for colder operating temperature, run colder spark plugs, and also redirect pcv oil vapors to a catch can. I every once in a while monitor the knock sensors for if they are retard timing at all and it basically never does. Sometimes under heavy load and high rpm it retards timing a few degrees, but it did that with stock engine parts and 91 tune on 91 fuel.

Hope this helped...lol

I would use the fuel that has gas in it[up]

i use shell 93 and i made the mistake, forced to, of useing 87 and for this whole tank it clugs hard randomly, i figured it was the gas and cant wait to empty this tank to get back to good gas and snrusnak put my thoery to words and beyond, so i would say listen to him/her (sorry not sure[confused]) haha[up]

+1 snrusnak [up]

snrusnak funny you said short as possible.. kinda lost me at the ... in the first line. Im fairly retarded when it come to this shit. I'll try the 89 but I have no breather reroute or cooler plugs etc.

What about a 400cc single cylinder, if I can comprehend that..i guess the 89 E free is a better choice the 93 with E????

i use shell 93 and i made the mistake, forced to, of useing 87 and for this whole tank it clugs hard randomly, i figured it was the gas and cant wait to empty this tank to get back to good gas and snrusnak put my thoery to words and beyond, so i would say listen to him/her (sorry not sure) haha

Click to expand...

HIM!!!! (I even double checked just to be sure...)

snrusnak funny you said short as possible.. kinda lost me at the ... in the first line. Im fairly retarded when it come to this shit. I'll try the 89 but I have no breather reroute or cooler plugs etc.

What about a 400cc single cylinder, if I can comprehend that..i guess the 89 E free is a better choice the 93 with E????

Click to expand...

Sorry lol...just was trying to put all the information in there.

89 straight gas is better than 93 blend IMO and in most people's opinion. That does not mean it is compatible with the buell though. The buell requires 91 octane or higher.

Basically, whatever the engine is specified to run on, you must use. The owner's manual calls for 91 octane(IIRC) for the buell's, so you need to use 91 octane. The specified octane is based on numerous things, mainly compression ratio and ignition timing. There may be an opportunity to "cheat" the octane rating and get a way with a lower octane if you have lower temperatures and no oil vapor in the intake.

Hopefully that sums it up.

You could try a tank of 89 but listen carefully for pinging. If the engine is pinging then you need to back off the throttle and ride easy through the tank, then fill up with the right fuel. Pinging/detonation CAN cause severe damage to the engine, primarily if it occurs at high rpm.

I would not recommend trying 89 octane on a 100% stock engine, though. When 100% stock, it is designed to run on 91 octane. You'd maybe get away with it with the colder plugs and breather reroute), but still that may be a stretch. These engines run hot since they are air cooled and need all the protection the higher octane provides. I run 93 in my buell and still get pinging sometimes like when I just sat in traffic for some time and it gets real hot.

Also, as far as the 400cc single cylinder dual sport, the same concepts apply. If it is all stock, then you need to run whatever octane is specified in the owner's manual.