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On a ride last week when I stopped for gas there was another Wing rider filling up his bike. There were three grades of fuel available at 87, 89, and 91 octane and he was using 91 octane in his bike. I filled up with the 87 grade as is my usual and he seemed to think that I was not being good to my bike by using the stuff that Honda says to use in it. Even though he admits that he can't tell the diff between regular and premium he seems to think that the higher octane fuel is somehow better for the bike. I guess that I could understand this if the bike did not run well on regular but it does.

So it made me wonder just what you guys are using regarding octanes. I have heard for years to use the lowest octane that your vehicle will run properly on. Is this true or not? :shrug:
 

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I have always run 87 octane. Book says 87, so if it's good enough for Mother Honda, good enough for me.
 

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87 works just fine for me!:thumbup::thumbup::thumbup:
 

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87 in the Wing.
And 87 in the VTX
 

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Take three pages to explain, but higher octane is actually harmful to the engine. It builds up more carbon.
 

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Take three pages to explain, but higher octane is actually harmful to the engine. It builds up more carbon.
that sounds intresting , I would have thought that higher octane would burn more complete
 

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Every drop has been 87 in my Wing.
 

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that sounds intresting , I would have thought that higher octane would burn more complete
The short answer is higher octane burns cooler. Does not burn off the carbon like lower octane.

Then you get into compression and stroke and all kinds of things.

But if you take the bike out and run it hard once in awhile none of it really matters as it will burn the carbon out with any octane. But as most do not run the engine to the red line very often, carbon will build more with high octane.
 

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87 for me tried them all. No extreme gains in mileage not worth the extra cost. :agree:
 

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87 Octane for me. Scared me at first to run 85 Octane while out west, but it worked ok.

Higher octane burns slower, you can actually be wasting fuel unless you have an engine designed for hi-octane fuel. Plus paying a higher price.

Awhile back, when fuel prices went to $4.00+ I used some middle grade (89 octane) in my Vette. It did not seem to bother it, since the computer corrects the timing.

But, I did have someone point out that not many cars today call for 89 Octane and lots of stations may have it in the ground longer than 87 or 91 Octane, and there is more of a chance of getting some bad fuel using that grade.

Just food for thought.:shrug:
 

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Higher octane, by definition, only reducing pre-ignition (pinging). Why use it if your engine doesn't need it? And if you think your engine needs it, then you have an engine problem that needs to be fixed.

Some vehicles (like the Vette, and my GTI) have knock sensors that will adjust for lower octane (which also reduces, slightly, performance). Generally, high compression or performance engines need the higher octane.
 
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Lower octane

The lower octane (85) in Colorado is because at a higher altitude, it equals the same as 87 at sea level. At least that is what I understand, so the 85 octane at 5,000 ft (Denver) is comparable to 87 at sea level.
 

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Take three pages to explain, but higher octane is actually harmful to the engine. It builds up more carbon.
This is an article taken from the VTX site. It spells out the octane issue in understandable terms:


What octane Gas should I use?
How to “Get Gas” without leaving skidmarks

by: Brian "Tapper" Davis

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 knocking. So the octane number has no bearing on the quality of the gas. But it does have a bearing, on how well your motor can utilize the gas and extract the maximum energy from it. However, getting too far into details of this would require a pretty damn big article, so I’m going to generalize a bit, for the sake of brevity here.

First, consider that gas burns faster under pressure. The more pressure, the faster it burns. Therefore, a high compression motor will burn gas faster than a low compression motor. The VTX is a relatively low compression motor folks. So, we don’t really want a slow burning gas.

Second, the burn timing in your motor is hugely important when considering how well the motor can develop power from a given amount of gas, and this timing is determined by the ECU, which can manipulate the spark advance of your engine. Normally, the timing in your VTX is pretty close to 8 degrees before top dead center, but the ECU can and does retard or advance the spark timing to respond to certain running conditions of the motor, like coolant temperature, rate of increase of Rpm’s, or any of a number of other conditions. But none of these parameters are accessible (yet) by you, the itinerant tuner. So, you have no way to manipulate the spark to match the burn speed of your gas. Since the VTX is designed by the factory to use 87 octane gas, if you run something different, the only possible way you have to tune your motor to use a different octane, is to manipulate the compression ratio of your pistons.

So here’s the thing: Unless you have changed the pistons in your VTX, a higher octane gas will have the effect of de-tuning the motor, and therefore reduce its performance. Now, the amount will probably be minimal, but it’s there. That’s the meat and potatoes guys, but there are a few more things we can infer. First, at higher altitude your compression will be slightly lower, and therefore you can get away with running a slightly lower octane gas. In fact, in areas like Denver, where the altitude is up around 5,000 feet, you’ll find gas stations selling 85 octane gas. But you’ll never find a gas station in Texas selling 85 octane. Since the altitude is much lower, the octane rating needs to be a little higher, so regular gas is typically 87 octane.

Second, gasoline quality is dependant on a lot of things, but octane isn’t one of them. In fact, there is almost no real difference in “premium gas” other than the octane number. Federal law dictates the amount and type of most of the additives in gas. So by definition, they’re all pretty similar in nature.

Except.

Gasoline is formulated according to climate in the US, and gasoline refiners use 6 basic formulations based on the expected temperature in the area they are expected to be sold in. Gas companies vary this by season, and by location (it also tends to be colder in Denver than in Dallas). So that gas you bought in Dallas might not give you great performance in Denver.

These days, unleaded oxygenated gas is far superior in performance and energy characteristics as compared to the old leaded gas of yesteryear. We generally have very good gasoline available to us at the pump.

Lastly, just remember this simple rule of thumb: You should always use the octane rating recommended by the manufacturer for your motor. But, if you are riding in a climate significantly different than sea-level at 80 degrees Fahrenheit, then use the lowest octane gas you can find that will not cause your motor to knock.

One more thing – many cars these days have anti-knock sensors built into them (the VTX doesn’t), and those sensors are used by the ECU to manipulate the spark timing. So, if you run an octane significantly different from the manufacturers recommended octane number, the ECU will detune the motor in real time, and you won’t get any knocking – but you absolutely will lose performance. Use the recommended gas. If you’ve been running a higher octane gas, and spending the dough to do it, then I hope this little article will save you some bucks, and in the process gain you some performance. Good luck!
Last update: 2005-06-22 15:43
Author: Tapper
 

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Take three pages to explain, but higher octane is actually harmful to the engine. It builds up more carbon.
:agree:Octane is a rating that shows detination and burn rate. High octane for high comression, lower octane for low compression.
Wings are low compression engines. Harley, BMW, some sport bikes and the European cars and bikes mostly use high comression, consult the owners manual. FWIW, if diesel had an octane rating, it does but isn't usually posted, it would be very high.

Best Wishes.
 

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My owners manual says 86 or higher. 87 is the lowest we have in Northern Virginia so that's what I use. Everything around here is also 10% ethanol as well. Heard on the radio yesterday, it will be raised to 15% soon. I'd prefer it not be raised...
 

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There we go with that falacy that MORE is better. More people is not better. More traffic on the road is not better. More octane in a wing is not better....but....some (especially public employees) think more is better. Well, more ain't better.

87 in the Wing
91 in the ST (cause it has a high compression engine).
 
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