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Discussion Starter · #1 ·
I put 87 octane in all my bike and never had a problem with knock pinging are anything.

At gas stations the attendant always hit the 93 button and I turn around and press the 87 button. They stay that all biker use 93 octane in there bikes. I told him I not every biker. An my bike runs damn good with 87 in her.

I have a stage two jet kit and vance & hine exhaust and it runs very excellent on 87. I do put some gas cleaner in there every month. But why spent the extra money for 93 when the manufactors built them to run on 87.

Just a thought
 

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Check the owners manual. My owners manual specifically says that 87 octane fuel is appropriate. It also says something about NOT adding fuel enhancers/cleaners such as octane boosters and fuel system cleaners. I don't think those mods would warrant an upgrade to a higher octane fuel... not sure though.

Just out of curiosity...why are you letting an attendant fuel your bike? :rolleyes
 

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Discussion Starter · #4 ·
Not letting him fuel it just pressing the buttons.

The only reason I using the cleaner, because is a old bike and I had to for only three months. When I got her she was in critical condition. Adjusted the valve, cleaner the carbs, adjusted the jet kit. She was spitting out fire and black smoke from the exhaust at IDLE.

I give it two more month and I stop with the fuel cleaner.
 

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Discussion Starter · #6 ·
Just for those that the manual say 87 and they use 90 or above.
 

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njdjh2o said:
Not letting him fuel it just pressing the buttons.
Man, what's next? People letting others doing oil changes? I know of a few cities around here that have town ordinances that REQUIRE attendants fuel vehicles so the riders can't, even if they wanted to.
 

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It depends on the bike. A lot of newer bikes are designed to run on higher octane, a lot of bikes are not. If the manufacturer tells you to use 87, then the smartest thing to do is run 87. If they tell you to run 93, then run 93. Not all engines are equal, and I figure that engineers who design them are a lot smarter than me. I run 87 in mine because that's what's recommended. Tried 89 and 91 for a while (before I knew that 87 was the recommended octane for my bike), and there was absolutely no benefit.
 

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I usually go by compression ratio. the bleeding edge bikes are running almost 13:1 compression, I would never run 87 octane in an engine like that...too much chance of detonation. for frame of reference, many cars that run 87 have 9.0:1 compression. newer cars generally have knock sensors to retard timing to compensate for fast burning 87 if the engine has is designed to run on 91+, but carb bikes definitely dont have this, not sure about EFI bikes... and anyways retarding the timing loses power.

I would wager that you should probably run premium in any powerful sportbike, while the harley crowd would be better off with 87.

in the end, as always, RTFM....
 

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GreenZED said:
I usually go by compression ratio. the bleeding edge bikes are running almost 13:1 compression, I would never run 87 octane in an engine like that...too much chance of detonation. for frame of reference, many cars that run 87 have 9.0:1 compression. newer cars generally have knock sensors to retard timing to compensate for fast burning 87 if the engine has is designed to run on 91+, but carb bikes definitely dont have this, not sure about EFI bikes... and anyways retarding the timing loses power.

I would wager that you should probably run premium in any powerful sportbike, while the harley crowd would be better off with 87.

in the end, as always, RTFM....
whats all this talk about retards? :lol




RTFM x2
 

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I had ot get my manual to double check, it says 86 or higher or 91+. If pinging occurs go to premium. I always pay for permium gas and will continue doing so.
 

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GreenZED said:
I usually go by compression ratio. the bleeding edge bikes are running almost 13:1 compression, I would never run 87 octane in an engine like that...too much chance of detonation. for frame of reference, many cars that run 87 have 9.0:1 compression. newer cars generally have knock sensors to retard timing to compensate for fast burning 87 if the engine has is designed to run on 91+, but carb bikes definitely dont have this, not sure about EFI bikes... and anyways retarding the timing loses power.

I would wager that you should probably run premium in any powerful sportbike, while the harley crowd would be better off with 87.

in the end, as always, RTFM....

A Hardley barley runs on 87 and it's recomended to run 93 or higher.

My Hondas recomend 87 on both.
 

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Ca$h said:
I had ot get my manual to double check, it says 86 or higher or 91+. If pinging occurs go to premium. I always pay for permium gas and will continue doing so.
Then you are potentially blowing perfectly good money right out of your exhaust.

Octane is just the measure of the heat and/or pressure required to spontaneously combust fuel vapors. To a lesser degree it also measures the amount of heat required to completely burn the fuel vapors. For the best performance and economy in any engine you should run the lowest octane rating that doesn't cause pinging. Running anything higher may to a very limited degree keep your engine cleaner and provide an imperceptable amount of additional power, but you're blowing more unburnt fuel out of your exhaust, and therefore aren't getting as much bang for your buck.
 

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Do you still have the original manual for that zx750? I think my hanes manual (don't have the original) said to use 91 or higher. The ex500 says that too. I did get some pinging on 87 (WOT only), and it did go away with 93, so I stuck with premium. My TL can run on 87 so that's what I use.

Actually, you loose a bit of power by going above your grade. Higher octange gas is less volatile, and extra additives displace that little bit of actual gasoline.. If you have a knock sensor then it's different, but i don't think any bike does.

And yes, I did have a bike that ran better on 87 than 93.
 

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Here' my no BS assessment of octane. Octane is like what some of the others said. It's a rating of a particular fuel's ignitiability. The lower the number the easier it is to ignite. So what about an engine requires the need to increase octane or have higher octane requirements? Compression ratio, nitrous, forced induction, and little talked about engine timing. Compression ratio is a given. The more you squeeze the air fuel mixture, the more heat energy is generated and thus the fuel can have a tendency to ignite on it's own just from the energy of squishing the air/fuel mixture atoms together. Having high compression alone isn't just a pre-requisite for needing higher octane. Smaller engines can get away with lower octane requirements and use higher compression. The reason is the amount of air/fuel drawn into each cylinder and the resulting speed of burn from the expanding flame front when the fuel is ignited. Nitrous is a given as the additional oxidizer present in the N2O molecule will cause a hotter burn and thus lower octane fuel will pre-ignite. Same goes with forced induction when you're squishing air into the cylinder. The compressed air also has residual heat energy that will pre-ignite fuel. Timing is another reason why higher octane may be required. Advancing ignition is done to achieve more power. Fuel doesn't burn cleanly or at 100% during the combustion cycle. As a result additional power can be had when you start the spark a bit early in the cycle before the piston reaches top dead center. But you don't want the entire mixture to ignite fully before the piston achieves top dead center. Hence why higher octane fuel is required in this application.

As you can see there is no simple answer to why you would run higher octane. If you haven't significantly modd'ed your bike, I would stick with the manufacturer's recommended octane for fuel. The only time you would deviate from that recommendation is if you are getting pinging and knocking when using the recommended fuel. Usually the cause of this is when the engine has some miles on it and there is signficant carbon build up in the cylinder head. The extra carbon acts like a layer that increased ultimate compression. Also peaks or ridges in the carbon layer can be localized hot spots which will also cause pre-ignition. With that in mind, don't ever run higher octane than is necessary. You can actually do more harm than good even if your car or bike has a knock sensor. Remember what octane is. Now you just put in fuel that is harder to burn in your engine. The result is a lot of unburned fuel that results in carbon build up in the cylinder heads and intake manifolds which will cause other problems in addition to possibly hurting HP output. So keep that in mind, higher octane fuel used incorrectly can cause more issues other than just burning a hole in your wallet.

To address another poster's discussion on EFI bikes. I'm not aware of any bikes out there that have knock sensors. Knock sensors should only be viewed as an ignition retard device. They only kick in when there is knocking present where by the ECM yanks timing from the engine. Most of the time, your ECM will run its programmed ignition advance to its fullest. I'm also not aware of any EFI bikes that have oxygen sensors. O2 sensors are probably the best enhancement for a EFI bike as the ECM can constantly monitor the air fuel mixture to make sure it is metering the appropriate amount of fuel into the engine for maximum power and fuel efficiency. I think the hold back with implementing O2 sensors is the required resolution needed for the typical bike that has high redlines.
 

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ZX10 thats pretty long but ill try to shorten it..


the lower the octane the easier it will combust from pressure rather than the spark from the spark plug. if it ignites from pressure, its called ping or engine knock. unless your manual says to use it, you are wasting money by buying higher octane than recommended.
 

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TRocket,

With my post, I also wanted to say that advancing the ignition timing will also require higher octane. Under that situation there isn't any pressure induced pre-ignition. But yeah. I can be very verbose sometimes. LOL.
 

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Lets try another explanation. The higher the octane, the slower the fuel will burn and the more resistant to lightoff caused by something other than the sparkplug (called pre-ignition and indicated by pinging.)

It is important that your fuel be matched to your ignition timing in order to light at the proper moment and completely burn during the firing stroke. Too soon (due to preignition) and its partly working against the engine (expanding on the compression stroke.) Too late and you're not transferrring full energy from the fuel/air mix to the wheels. Either way, power is wasted. And the former is harmful to the engine as well.
 
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