I have used 87 octane in my 2001 883 since I bought it. Yestrday for the hell of it I put in 89 octane, and I know you will think Iam nuts but I felt the difference right away. Iam, not going to 91 but I will keep running 89 octane from now on.

 

Good for you. I run what the manufacturer recommends.

 

Why not just run 91? You can't tell me you can't afford an extra 10 cents per gallon... I run 91 all the time. Just think how much money you are saving by riding your bike than driving.

 

I understand . I run 93 whenever possible .When I have to put 87 in (caseys) my bike runs bke runs like crap and my mpg drops 5 mpg

 

I guess some things never change.
I've never had any air cooled engine run well on any gas from Caseys when I was getting gas from them all the way back in the early 80s to the late 90s.
I don't live in the midwest anymore so no more Caseys for me.

 

the book for 06 says 91. i have run 91 and 93 w/ no difference. never have run lower octane. only $ 2.99 a gallon in texas. ride all day for 8 or 9 bucks.
stay safe

 

Only $2.99 a gallon?It's the same around here but I think the price of gas sucks.5 years ago it was $1.01-1.05 a gallon.At this rate in 5 more years it will be about $13 a gallon.I can only hope my wages can keep up with the economy.

 

Here is a copy of one of the best explanations of octane I have read. Octane is widely misunderstood because it is not what the gas companys claim it to be.
Sorry folks, it came from a Honda forum, but it applies to all bikes anyway.



How to “Get Gas” without leaving skidmarks

One of the most frequently misunderstood issues among the VTX community, and indeed among all folks concerned with performance and appropriate care and feeding of their motors is the subject of gasoline, and more specifically the mysterious octane number. Oil companies have gone a long way to foster this mystery, by marketing gasoline with higher octane numbers as “premium”, and inferring that the golden road to more performance, cleaner widgets, and hot chicks, is to spend the extra dough on the higher-octane stuff.

Well, sorry to be the one to break this to you, but you’ve been had. So lets take a quick look at octane, and then get to the big point – what should you run in your VTX?

Now the truth is, octane is actually a chemical, which comprises an important part of the chemical soup that is gasoline. But here’s the thing – octane the chemical has absolutely nothing to do, with “octane” the pump measurement. So what is it?

In a nutshell, the octane rating of a fuel is a measure of its ability to resist detonation, ping, pre-ignition, or knock.

The number we most often associate with octane is the "Anti-Knock Index", or the "Pump Octane" number. This rating is an average of two different measurements - the Motor Octane Number, and the Research Octane Number. Both of these measurements are taken using a special single cylinder test engine that has a variable compression ratio. The RON measures the knock resistance of a fuel during low RPM, light load conditions, while the MON is representative of high-speed, high load operation. As a result the MON will always be lower than the RON, but for our purposes the Research Octane Number is more significant because it more closely represents the way a low rpm V-twin motor is operated.

So “Octane”, has absolutely nothing to do with the energy content or quality of gasoline. It’s just a measurement of when the gas will make a motor of a specific configuration begin to knock.

Lets take a moment here to define a couple of things important to understanding this discussion.

Knocking (also called pinking or pinging) in internal combustion engines occurs when fuel in the cylinder is ignited by the firing of the spark plug but burns too quickly, combusting completely before the optimum moment during the compression phase of the four-stroke cycle. The resulting shockwave collides with the rising piston, creating a characteristic metallic "pinging" sound. The fuel is normally ignited slightly before the point of maximum compression (the spark advance) to allow a small time for the flame front of the burning fuel to expand throughout the mixture, so that maximum pressure occurs at the point of maximum compression. It is only when this flame front arrives too early, for whatever reason, that the knocking effect occurs. If allowed to persist, knocking can cause vibration and damage to engine parts.

Knocking is a different phenomenon from pre-ignition, which occurs when the air-fuel mixture in the cylinder ignites before the spark plug fires. Pre-ignition is caused by heat buildup in engine components or overheating of the air-fuel mixture during compression, and cannot be prevented by delaying spark plug firing. As such, if pre-ignition is allowed to continue for any length of time, severe engine damage can result. Pre-ignition is bad bad stuff, and changing the octane of the gas won’t affect it.

Generally speaking, a higher-octane gasoline prevents knocking by either slowing the burn rate of the gas, or by increasing the difficulty of lighting it up. The idea here is to prevent the gas from burning too fast, and causing knoc

 

exactly. higher octane prevents detonation particularly at higher temps and load. Higher the ambient temp, the higher the octane.

 

Good article. I've always thought that performance gain from using higher octane in a stock motor was psychological. Ever notice how your car seems to run better after it's washed?