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Regarding fuel, what is an octane number? What does the octane number mean? What type of octane fuel do you really need?

Do we need to worry about knocking sounds when it comes to motorcycles?

Is this more of a concern with dirt bikes than street bikes?
 

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The most important characteristic of gasoline is its octane rating, which is a measure of how resistant gasoline is to premature detonation in an internal combustion engine, also known as knocking.

Engine deposits can be avoided by using the proper octane and detergents. You can buy detergents to add to your gas or you can go with a company that has passed the independant top tier testing.

http://www.toptiergas.com/

I've never put anything other than 93 octane fuel that is top tier approved...in my area that's Shell, Chevron, and Texaco.
 

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The most important characteristic of gasoline is its octane rating, which is a measure of how resistant gasoline is to premature detonation in an internal combustion engine, also known as knocking.

Engine deposits can be avoided by using the proper octane and detergents. You can buy detergents to add to your gas or you can go with a company that has passed the independant top tier testing.

http://www.toptiergas.com/

I've never put anything other than 93 octane fuel that is top tier approved...in my area that's Shell, Chevron, and Texaco.
+1 It is just how resistant the gas is to the spark Higher the octane the more resistant it is to detonation.

And it really makes no difference between dirtbikes and streetbikes. It can cause damage to both, because if the gasoline detonates before the piston hits top dead center the piston will be thrown back downwards while its trying to move upwards. In other words its like force on force which isnt good.
 

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Heres a more in depth article.

"Octane rating

The most important characteristic of gasoline is its Research Octane Number (RON) or octane rating, which is a measure of how resistant gasoline is to premature detonation ( knocking). It is measured relative to a mixture of 2,2,4-trimethylpentane (an octane) and n- heptane. So an 87-octane gasoline has the same knock resistance as a mixture of 87% isooctane and 13% n-heptane.

There is another type of Octane, called "Motor Octane Number" (MON), which is a better measure of how the fuel behaves when under load. Its definition is also based on the mixture of isooctane and n-heptane that has the same performance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 10 points lower than the RON. Normally fuel specifications require both a minimum RON and a minimum MON.

In most countries (including all of Europe and Australia) the 'headline' octane that would be shown on the pump is the RON: but in the United States and some other countries the headline number is the average of the RON and the MON, sometimes called the "roaD Octane Number" or DON, or (R+M)/2. Because of the 10 point difference noted above this means that the octane in the United States will be about 5 points lower than the same fuel elsewhere: 87 octane fuel, the "normal" gasoline in the US and Canada, would be 92 in Europe.

Romania is a supplier of "light-sweet" crude oil, which, when distilled, resulted in a gasoline with an 87 rating (DON).

It is possible for a fuel to have a RON greater than 100, because isooctane is not the most knock-resistant substance available. Racing fuels, Avgas and LPG typically have octane ratings of 110 or significantly higher.

It might seem odd that fuels with higher octane ratings burn less easily, yet are popularly thought of as more powerful. Using a fuel with a higher octane lets an engine be run at a higher compression ratio without having problems with knock. Compression is directly related to power, so engines that require higher octane usually deliver more power. Some high-performance engines are designed to operate with a compression ratio associated with high octane numbers, and thus demand high-octane gasoline. It should be noted that the power output of an engine also depends on the energy content of its fuel, which bears no simple relationship to the octane rating. Some people believe that adding a higher octane fuel to their engine will increase its performance or lessen its fuel consumption; this is false - engines perform best when using fuel with the octane rating they were designed for.

The octane rating was developed by the chemist Russell Marker. The selection of n- heptane as the zero point of the scale was due to the availability of very high purity n-heptane, not mixed with other isomers of heptane or octane, distilled from the resin of Jeffrey Pine. Other sources of heptane produced from crude oil contain a mixture of different isomers with greatly differing ratings, which would not give a precise zero point."
 

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Hi UpNSmke, seems you know a lot about fuels! You a chemical engineer in the petrochemical industry???

I used to have my own flying school here is SA (Secunda), and it is amazing how many guys come to the airfield for AVGAS thinking it will increase their performance, which on a normal standard roadcar it doesn't. As you say, the vehicle's compression ratio should be high enough to take advantage of high octane rating.

As far as I know, AVGAS has a lot of other additives in it to prevent high altitude "boiling", which actually reduces the efficiency of the fuel (calorific value), is this so??

I also used to compete in the local Motorcycle Economy runs in the early 1980's and the tests that I did those years showed that the lowest octane rating fuel that you can get away with, will indeed give you the best efficiency. During testing I actually added a small amount of diesel with the 87 octane fuel and got significant better fuel economy. (But not if the weather was too cold though. Had to shroud the engine partially to maintain heat in the engine. Moto Guzzi 850 Le Mans 3)

Thanks for the info. Great!!
 

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Hi UpNSmke, seems you know a lot about fuels! You a chemical engineer in the petrochemical industry???

I used to have my own flying school here is SA (Secunda), and it is amazing how many guys come to the airfield for AVGAS thinking it will increase their performance, which on a normal standard roadcar it doesn't. As you say, the vehicle's compression ratio should be high enough to take advantage of high octane rating.

As far as I know, AVGAS has a lot of other additives in it to prevent high altitude "boiling", which actually reduces the efficiency of the fuel (calorific value), is this so??

I also used to compete in the local Motorcycle Economy runs in the early 1980's and the tests that I did those years showed that the lowest octane rating fuel that you can get away with, will indeed give you the best efficiency. During testing I actually added a small amount of diesel with the 87 octane fuel and got significant better fuel economy. (But not if the weather was too cold though. Had to shroud the engine partially to maintain heat in the engine. Moto Guzzi 850 Le Mans 3)

Thanks for the info. Great!!
Nah man I wish since I am only 18 haha. I just do alot of reading on mechanics and how stuff works.
 
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