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When (if) I get a bike, what octane rating would you get? what is the significance in higher octane rating. Where I live, we have 87, 89, 91, but never any 93. Is there a true performance difference in getting 91 as opposed to 87? speaking of both bikes and cars.

what about oil? I heard synthetic oil is better? is there a difference?

thanks. :)
 

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Ocatne- Use what the bike calls for. When I first got my GSX-R600, I was running 93 in it. I happened to notice on the frame that it called for 87, so I switched. After a couple of tank fulls, I noticed it was running better and I picked up 4mpg.

Oil- This is a huge barrel of worms, and you just opened it. The biggest thing about synthetic is never use it before 5k miles, or that what most say atleast. Now, the biggest thing with oil period, DO NOT, use an oil that says "energy conserving", in that little circle on the back of the bottle. That means it has friction modifiers, which will cause problems with a wet clutch. As long as you change your oil, on time, everytime, use whatever oil you like best.

I personally run, Rotella T 15W-40 in my bike, and like the results I've had with shift quality.
 

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Use the octane rating that your bike's manual specifies, not any higher. If you go to a high elevation like where I live, use a lower octane. The lower octane you use the better gas milage/more power you will have. All octane ratings mean is their resistance to burning. If you use too low of octane, you will get pinging and detonation which can destroy your engine because the fuel is igniting early, hence it is too combustable.

Oil, you should use dino oil to break it in, then switch to synthetic after a few thousand miles as I understand. However, as long as you change oil regularly, I don't think it really matters. There have been many threads on this topic, so do a search.
 

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Like they said too low octane=detonation too high and your blowing away money . 89 should be your best bet or 87. I'm almost positive you wont have any problems but i would go with 87 until you look int your owners manual.

later
peace
john.g
 

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I only run 91 in my bike

why not, it's only a couple of extra $'s

as far as fuel consumption, yes you will get more with 87, but that only has to do with the fact that higher octane gas ignites easier anyhow (or at least that's my understanding)
 

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Leb_CRX said:
I only run 91 in my bike

why not, it's only a couple of extra $'s

as far as fuel consumption, yes you will get more with 87, but that only has to do with the fact that higher octane gas ignites easier anyhow (or at least that's my understanding)
Higher octane has a higher flash point, meaning it is harder to ignite. That's why you should only move up one range of octane, if you are having spark knock.

Don't feel bad though, thats what most people think too. I've seen guys dump 2 bottles of octane booster in their tank thinking it's going to add more power.
 

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Here is an article Ducman posted on the old board here http://www.stuntbikes.net/archives/forums/showthread.php?t=142204 about the octane topic.
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In many high-performance situation, riders clamor for higher octane fuels, thinking this will give them additional horsepower and, thus, an advantage over the competition. But this is not the case--adding higher-octane race fuel to your motorcycle may actually produce less horsepower. Here's why: Octane, an arbitrary number which is calculated as the average of the Research Octane Number (RON) and the Motor Octane Number (MON), and is only an indic ation of a fuel's sensitivity to knock, which is typically pressure-induced self-ignition. (Of these two ratings, MON is more applicable to racing fuels as it is measured under high load and high speed conditions.)

Octane, as you can see, is not a measure of how much power--or, more correctly, specific energy--is contained in a fuel. And remember that leaded high-octane race fuels burn slower than most unleaded fuels, and may reduce performance in stock or lightly modified motorcycles. A high octane rating itself, however, does not mean that the fuel is slow burning. Hence, it has no direct bearing on the power characteristics of the fuel.

The knock tendency (and hence, the Octane rating) of a fuel is a function of the amount of free radicals present in the fuel prior to ignition and can be reduced by the addition of tetra ethyl lead, aromatics and other additives.

Although some racing organizations still use maximum octane number as the discriminating factor for fuel legality, it is really not appropriate for racing purposes.

Instead one should look at the amount of energy (heat) released in the burning of a particular fuel. This is described by the specific energy of the fuel. This quantity describes the amount of power one can obtain from the fuel much more accurately. The specific energy of the fuel is the product of the lower heating value (LHV) of the fuel and molecular weight of air (MW) divided by the air-fuel ratio (AF):

Specific Energy = LHV*MW/AF

For example, for gasoline LHV= 43 MJ/kg and AF=14.6, while for methanol LHV= 21.1MJ/kg (less "heat" than gasoline) and AF=6.46 (much richer jetting than gasoline). Using the above formula we see that methanol only has a 10% higher specific energy than g asoline! This means that the power increase obtained by running methanol, with no other changes except jetting, is only 10%. Comparing the specific energy of racing and premium pump gas you can see that there is not much, if any, difference. Only alcohol s (such as methanol or ethanol) have a slightly higher specific energy than racing or pump gas.

Other oxygen-bearing fuels, besides the alcohols and nitromethanes, such as the new ELF fuel, will also produce slightly more power once the bike is rejetted. However, at $15.00 to $20.00 at gallon for the fuel the reportedly minor (1% - 2%) improvement is hardly worth the cost for the average racer.

The real advantage of racing gasolines comes from the fact that they will tolerate higher compression ratios (due to their higher octane rating) and thus indirectly will produce more power since you can now build an engine with a higher compression rati o. Also, alcohols burn cooler than gasoline, meaning even higher compression ratios are possible with them, for even more power.

The bottom line here is that, in a given engine, a fuel that doesn't knock will produce the same power as most expensive racing gasolines.

However, it sometimes happens that when you use another fuel, the engine suddenly seems to run better. The reasons for this are indirect: First, the jetting may be more closely matched to the new fuel. Secondly, the new fuel may improve the volumetric e fficiency (that is, the "breathing") of the motor. This happens as follows: Basically a fuel that quickly evaporates upon contact with the hot cylinder wall and piston crown will create additional pressure inside the cylinder, which will reduce the amount of fresh air/fuel mix taken in. This important--but often overlooked--factor is described by the amount of heat required to vaporize the fuel, described by the 'enthalpy of vaporization' (H), or 'heat of vaporization' of the fuel.

A high value of H will improve engine breathing, but the catch is that it leads to a different operating temperature within the engine. This is most important with two-strokes, which rely on the incoming fuel/air mix to do much of the cooling--even mode rn water-cooled two-strokes rely on incoming charge to cool the piston. For two-strokes a fuel that vaporizes, drawing a maximum amount of heat from the engine, is essential--the small variations in horsepower produced by different fuels is only of second ary concern.

Also important is the flame speed: Power is maximized the faster the fuel burns because the combustion pressure rises more quickly and can do more useful work on the piston. Flame speed is typically between 35 and 50 cm/sec. This is rather low compared to the speed of sound, at which pressure waves travel, or even the average piston speed. It is important to note that the flame propagation is greatly enhanced by turbulence (as in a motor with a squish band combustion chamber).

The most amazing thing about all this is that you can get the relevant information from most racing gasoline manufacturers. Then, just look at the specification sheet to see what fuel suits you best: Hot running motors and 2-strokes should use fuels wit h a value of "H" that improves their cooling, while more power (and more heat) is obtained from fuels with a high specific energy.

By the way, pump gas has specific energies which are no better or worse than most racing gasolines. The power obtained from pump gas is therefore often identical to that of racing fuels, and the only reason to run racing fuels would be detonation probl ems, or, since racing fuels are often more consistent than pump gas--which racers call "chemical soup"--a consistent reading of the spark plugs and exhaust pipe.
 

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yakky said:
You should look into doing some more research. Higher octane fuel burns more slowly and contains less energy. The only reason you would want to use a higher octane fuel is to prevent pre-ignition. Google search... try it once.

I don't know about his bike.. but i know the 2003 - 2004 R6 recommended for 91 octane so he might be right in using 91
 

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Gixxer_Six2003 said:
My FZR called for 91 on a sticker, on the inside of the left tail panel. But I'm not sure which 91 it means.

For example, check out this pic of the Zuki service manual for my Gixxer. I don't completly understand the different ways of rating.
The (R+M/2) method of calculating octane is what is used in the US. All pump stickers state this (the pump method?). The "R" is the Research method and is always higher. I believe it is the method used in Europe which is why they always talk about 93 and 95 (or even higher) octane. The sticker you posted means that you can use 87 octane from US pumps (R+M/2) method.
 

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Gixxer_Six2003 said:
Higher octane has a higher flash point, meaning it is harder to ignite. That's why you should only move up one range of octane, if you are having spark knock.

Don't feel bad though, thats what most people think too. I've seen guys dump 2 bottles of octane booster in their tank thinking it's going to add more power.
ahh ok cool, I had it backwards :)
 

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Not using synthetic oil during break in is the same myth as higher octane = more power. Porsche runs it Mobil One right from the factory.
 

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it depends on the piston rings. There are i believe, 3 different piston rings(material) and they have their own characteristics in which oil is needed for break in.
 

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Mikael said:
Not using synthetic oil during break in is the same myth as higher octane = more power. Porsche runs it Mobil One right from the factory.
Rings need a calculated amount of friction from contact with a properly finished cylinder wall to properly seat. Porsche (and a small handful of other manufacterers) run mobil one from the factory BASED on the honing procedures they use, ring type and oils' friction properties in the cylinder. The oil an engine is filled with from factory IS the oil type the engine should be broken in with.
 

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I have a zx9 and it calls for above 90 oct. I will be changing my oil pretty soon does it really matter what type.
 

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What everyone else has said. Use the lowest octane you can get away with....just never go below the manufacturer recommendations. And make sure youre running the same heat range on your spark plugs, and dont have any ignition timing devices, etc. Bumped timing or non-stock heat range plugs will change your octane requirements. I imagine units like a power commander will do this as well, although I'm not sure if a power commander alters ignition timing. I might imagine so.

Oil, the same. Use the factory viscosity rating..... Break it in with what the factory recommends....and keep dinosaur oil in it for a little bit. Im not switching to synth til between 6000 and 9000 miles, depending on my oil change schedule. Im at 2100 right now. As far as brand goes...as long as its a good brand, and MEANT for motorcycles...Id say the viscosity rating and the maintenance interval matters far more than specific brand. I hear generally good things about Silkolene...thats what Im running at the moment.
 
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