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When I bought my Vulcan 900 classic the previous owner suggested me to use premium gas because he used it. Now my motorcycle has about 10,000 miles on it. Is it a good idea to switch to the regular gas now? What are the downsides of doing that. Please suggest.
Thanks
 

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When I bought my Vulcan 900 classic the previous owner suggested me to use premium gas because he used it. Now my motorcycle has about 10,000 miles on it. Is it a good idea to switch to the regular gas now? What are the downsides of doing that. Please suggest.
Thanks
Shoulda been running regular the whole time. I think you'll be fine. Prolly notice more power too.

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I ran my 900 Custom on "regular" for almost 30,000 miles... that's all they need. You shouldn't have any problems at all with the switch, and you'll enjoy a few more nickels in your pocket!
 

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Please correct me if I am wrong, as my wife frequently tells me I am, but on page 31 of the owners manual it says "Your Kawasaki engine is designed to use only unleaded gasoline with a minimum octane rating of RON 91."
I was using 85 for a long time and had problems with mpg, as well as a slight hesitation at random times. After reviewing the manual and switching to a higher octane (91) the hesitation has gone away. I also get much better mpg, but I suspect that is due to the change in my fuel processor.
Anyway take it for what its worth.
 

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Please correct me if I am wrong, as my wife frequently tells me I am, but on page 31 of the owners manual it says "Your Kawasaki engine is designed to use only unleaded gasoline with a minimum octane rating of RON 91."
I was using 85 for a long time and had problems with mpg, as well as a slight hesitation at random times. After reviewing the manual and switching to a higher octane (91) the hesitation has gone away. I also get much better mpg, but I suspect that is due to the change in my fuel processor.
Anyway take it for what its worth.
The manual is based on the RON rating, however US gas stations list octane ratings using the (RON+MON)/2 forumula. RON of 91 is equivalent to ~87 octane using the (RON+MON)/2 formula. (short explanation)

I ran a couple of tests with tanks using 87, 89 and 91 octane (separate tanks) and found that my mpg actually went down slightly with the 91, but ran a bit better/equal with 87 or 89. From that point forward, I ran 87 exclusively, and depending on how agressive I was with the throttle, ran anywhere from 44-48 mpg on a regular basis. Babying the throttle, I could get up to 53.

85 is a bit below the minimum recommended 87 (91 RON), so I could see some issues potentially occurring there, with knock/ping in some circumstances.
 

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with mine i get better mpg with higher octane, plus runs much cleaner, less chance of the engine getting all gunked up
 

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The manual is based on the RON rating, however US gas stations list octane ratings using the (RON+MON)/2 forumula. RON of 91 is equivalent to ~87 octane using the (RON+MON)/2 formula. (short explanation)

I ran a couple of tests with tanks using 87, 89 and 91 octane (separate tanks) and found that my mpg actually went down slightly with the 91, but ran a bit better/equal with 87 or 89. From that point forward, I ran 87 exclusively, and depending on how agressive I was with the throttle, ran anywhere from 44-48 mpg on a regular basis. Babying the throttle, I could get up to 53.

85 is a bit below the minimum recommended 87 (91 RON), so I could see some issues potentially occurring there, with knock/ping in some circumstances.
Thanks for the response!
 

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Octane has nothing to do with how much "energy" a gallon of gas can deliver. Octane is simply a measurement of a gasolines resistance to pre-detonation. Also there are 3 major scales for measuring Octane - RON, MON, and AKI. Whenever you are talking octane, you have to know what scale you are using and comparing against. When I had my old NightHawk back in the late 80's, the owners manual said to use only 93 RON - which sounds bad, but translates to roughly 86.5 on the US scale!

In very high compression engines (as 10.5 to 1 or greater), temperatures in the cylinder during the compression stroke can get very high - high enough to cause the gas to ignite before the stroke is complete and before the spark fires. This leads to knocking, loss of power, and terrible mpg - not to mention engine damage eventually.

The 900 engine has a compression ration of 9.5 to 1, so there is not enough heat generated by the compression stroke to ignite 87 or 89 octane gas (remember your high school physics? the more you compress a gas the hotter it gets).

Interestingly, older bikes and cars get better performance with higher octane because they have a lot of carbon buildup on the valves and cylinder heads, thus reducing the amount of open space in the cylinder - which increases the compression - which pre-detonates the gas!

Best advice - save your money - run 87, and every few fill-ups put some Seafoam or other cleaner to keep the cylinder heads and valves clean.


Doc
 

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^thank this guy^

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Thanks Boomer! I've had this octane discussion with tons of riders, and almost all of them are (or were) absolutely convinced that higher octane meant "better" gas and more energy. They kept using the term "premium" fuel, which makes is sound better, but is really no different that regular, it just has different anti-knock additives.

If you've got money to burn - by all means try the hi-test stuff. But if your bike does not knock or ping with 87 - save your money!

Doc
 

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Thanks Boomer! I've had this octane discussion with tons of riders, and almost all of them are (or were) absolutely convinced that higher octane meant "better" gas and more energy. They kept using the term "premium" fuel, which makes is sound better, but is really no different that regular, it just has different anti-knock additives.

If you've got money to burn - by all means try the hi-test stuff. But if your bike does not knock or ping with 87 - save your money!

Doc
I'm on a 1600 so I'm still in a test phase. Although I have an 08 and I've heard some here and there's on it being a lil different to avoid pinging. Sigh.....other than that I'm tired of the octane subject. At least find out WHY its 93 and WHY its 87 and just WHY lol

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Thanks Boomer! I've had this octane discussion with tons of riders, and almost all of them are (or were) absolutely convinced that higher octane meant "better" gas and more energy. They kept using the term "premium" fuel, which makes is sound better, but is really no different that regular, it just has different anti-knock additives.

If you've got money to burn - by all means try the hi-test stuff. But if your bike does not knock or ping with 87 - save your money!

Doc
Actually it is different. Low octane gasoline is made from low octane blend stock, high octane gasoline is made from high octane blend stock. The additives don't have anything to do with it, unless you add ethanol, which raises the octane.
 

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Actually it is different. Low octane gasoline is made from low octane blend stock, high octane gasoline is made from high octane blend stock. The additives don't have anything to do with it, unless you add ethanol, which raises the octane.
Ethanol is considered an anti knock additive.

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Discussion Starter #17
Thanks a lot Doc for the detailed information. I have started using the regular gas from today. So far so good.

Octane has nothing to do with how much "energy" a gallon of gas can deliver. Octane is simply a measurement of a gasolines resistance to pre-detonation. Also there are 3 major scales for measuring Octane - RON, MON, and AKI. Whenever you are talking octane, you have to know what scale you are using and comparing against. When I had my old NightHawk back in the late 80's, the owners manual said to use only 93 RON - which sounds bad, but translates to roughly 86.5 on the US scale!

In very high compression engines (as 10.5 to 1 or greater), temperatures in the cylinder during the compression stroke can get very high - high enough to cause the gas to ignite before the stroke is complete and before the spark fires. This leads to knocking, loss of power, and terrible mpg - not to mention engine damage eventually.

The 900 engine has a compression ration of 9.5 to 1, so there is not enough heat generated by the compression stroke to ignite 87 or 89 octane gas (remember your high school physics? the more you compress a gas the hotter it gets).

Interestingly, older bikes and cars get better performance with higher octane because they have a lot of carbon buildup on the valves and cylinder heads, thus reducing the amount of open space in the cylinder - which increases the compression - which pre-detonates the gas!

Best advice - save your money - run 87, and every few fill-ups put some Seafoam or other cleaner to keep the cylinder heads and valves clean.


Doc
 

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this concept drives me nuts.... I am in agreement with the OP... if it says 91+ why would 87 be ok, yet... I will agree that depending on who you "talk" to even with marine engines some say run high test others say its full of additives and it screws up stuff....I personally found with my older boat motor premium ran awesome but I have been putting 90+ in my bike and think maybe 87 is ok?:mad::confused:
 

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Actually it is different. Low octane gasoline is made from low octane blend stock, high octane gasoline is made from high octane blend stock. The additives don't have anything to do with it, unless you add ethanol, which raises the octane.
Sorry, but it's not.

<snip>

Using high-octane gas in a car designed for regular accomplishes little except more rapid combustion of your money. Some refuse to believe this, claiming, for example, that premium gives the family Toyota better mileage or more power. These people are in dreamland. Others say premium is purer or contains detergents that will cleanse your engine of uncouth deposits. Likewise misguided thinking--government regulations require detergents in all grades of gasoline. (BP Amoco, I notice, asserts that its premium gasoline contains more detergents than legally required; if you think that's worth 20 extra cents a gallon, be my guest.) Some automotive types claim that using premium in a car designed for regular will make the engine dirtier--something about deposits on the back side of the intake valves. I've also heard that slower-burning high-octane gas produces less power when used in ordinary cars. Believe what you like; the point is, don't assume "premium" means "better."

<snip>


this is just one paragraph from a pretty decent article on gasoline : http://www.straightdope.com/columns/read/2565/whats-the-difference-between-premium-and-regular-gas

Two HS buddies who are now engineers with Chevron back all this up - the gasoline produced in the US is transported from city to city, and even across the country via underground pipeline - and they only transport one type of gas. It is at the end point where that gas is blended with the detergents and additives that make it unique to that brand, and that's where it's give it its octane properties.

Doc
 

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this concept drives me nuts.... I am in agreement with the OP... if it says 91+ why would 87 be ok, yet... I will agree that depending on who you "talk" to even with marine engines some say run high test others say its full of additives and it screws up stuff....I personally found with my older boat motor premium ran awesome but I have been putting 90+ in my bike and think maybe 87 is ok?:mad::confused:
Here is why running 87 is ok in north america...


The manual is based on the RON rating, however US gas stations list octane ratings using the (RON+MON)/2 forumula. RON of 91 is equivalent to ~87 octane using the (RON+MON)/2 formula. (short explanation).
 
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