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Discussion Starter #1
Octane=resistance to spark knock.
use 90 to 94 anything higher is a waste of money, 100 and your getting into race fuels, unless you have forged rods, Ti pins, ans mains, I would avoid it.
 

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A friend mixes race fuel with super unleaded all the time on his race bike or just runs it on race fuel, its a 99 zx6r stock internals. He hasnt had any problems.
 

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What's up, I tried posting a similiar question on the newbie forum but notta. I just want to know if anybody runs 100 octane or higher on a fairly regular basis, track use, or whatever. I just bought an 03 zx6r. Thanks. :)




Everything in moderation.
 

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Discussion Starter #4
Originally posted by minytrker

A friend mixes race fuel with super unleaded all the time on his race bike or just runs it on race fuel, its a 99 zx6r stock internals. He hasnt had any problems.
I should state that I am speaking as a GM tech at a dealership. I certainly am NOT a motorcycle mech. Maybe it works fine in a bike engine. We ran VP C-10 in our IMSA Modified so one of the guys on the team decides he'd put it in his K2500 and ended up doing some damage. Then again thats a 9.5/1 enging with a redline less than half of what our bikes do. Perhaps I stand corrected. I still say for a street bike, anything over an octane of 94 is a waste. Octane does not make your engine faster it is simply a measurement of a fuels resistance to pre-ignition. (spark knock)
 

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In Australia our prmium unleaded fuel is 98 octane without any additives and i've ran it on all my two-strokes and my '03 636 with no hasselse just more throttle response .
 

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Discussion Starter #6
Originally posted by barnes

In Australia our prmium unleaded fuel is 98 octane without any additives and i've ran it on all my two-strokes and my '03 636 with no hasselse just more throttle response .
I was referring to the additives in non-oxygenated racing fuel. Generally you dont find octane levels over 94 in the US unless it is a racing mix. VP MR8 is great for a two stroke I ran it in my RM125.
Anyway, I was probably wrong to begin with, I apprieciate you and minytrker giving a heads up though. :)
 

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Hey, thanks for the info fellas. I'll probably stick with around 94.
Sorry, it took so long for me to get back here I got lost in that other forum,(I swear I didn't know how to get out of there) you know, the one that says bikes and babes. But its really just a bunch of fine asss nskeds biytch eatij pusyes andd porrne damnn keeys aare stiicken!:D
 

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One thing that doesn't get discussed much concerning fuels is volatility. Race fuels do have higher octane ratings (Which helps keep combustion chamber cooler which helps avoid detonation at higher compression ratios) but they also have a higher volatility, which is to say they vaporize quicker (See where this is going?) The quicker a fuel atomizes the better it will combine into an even burning mixture at higher RPM and theoretically make more HP at higher RPM. I ran Fast Gas in a racing quad and had to change my jetting to keep it from running lean. So if you do run race fuels make sure you change you MAP so your mixture is good. (This could be why some have been having difficulty with backfiring when letting off the throttle with their pcIII's and full exhaust. The maps may have been made using higher volatility fuel so when you use pump gas unatomized fuel doesn't get burned completely and is passed into the exhaust where it explodes in the pipe)
 

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Originally posted by scootergmc

And in other countries Octane ratings are calculated differently.
Really?
I was already wondering if the euro spec kawi is different somehow since it says minimum 95 octane, as does my 02 636. Maybe you just explained why. Do you know this for a fact?
We have 95 and 98 octane pump gas here.
 

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kc8cks[/i]
I dont know where to start. Either giving the correct info on octane or reaming out kc8cks for tryin to sound like he knows what hes talkin about. It looks like he was copyin out of a service book and got all the info mixed up. You can get race fuels in almost any octane, 87-110. The octane is a measure of resistance to detonation, or how easily a fuel will burn. Higher octane fuels DO NOT burn as easily as lower octane fuels, there more difficult. High octane fuels are for high compression engines. High compression=more heat during the compression stroke and more heat will pre-igniite lower octane fuels. This is called predetonation. The fuel actually ignites before the spark plug sparks. The piston is not in the prime location and you actually lose power. Higher octane fuels resist combustion and if used in the wrong engine you can lose power. High compression engines get there power from squezing the air fuel mizture more and getting a bigger explosion as a result. So the compression is greater there will be a tendancy for the fuel to detonate prematurely, so a higher octane is needed.
 

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Guess that's a good reason one shouldn't post while blistered on Jim Beam.. Sorry. Did find out why I had to re-jet for the fast gas though. Difference in specific gravity caused the float to rise higher lowering the level in the bowl.
 

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High octane isn’t a magical boosting agent. The only reason you should go with higher octane is if your engine is knocking. Octane is simply just a detonation retardant- however this is not to say that it burns slower. The higher the octane, the more resistant the fuel is to premature detonation (ignition before the spark plug fires). But once the spark plug fires, high octane fuels will burn just as quickly as any lower octane fuel. In racing, high compression engines (which put out more HP then low compression engines) need higher octane fuel to keep the fuel from igniting prematurely. People want to think that if fast cars use high octane, then this must mean high octane is what makes the car go fast. This is not true. It is the higher compression engine inside these cars that make them go fast, and it just so happens that they require higher octane fuel. An easier way to picture this would be to think of the pistons. In a higher compression engine the pistons need to be stronger to withstand all the pressure. So, would you think that you could make your car go faster without doing anything to it except putting in stronger pistons? No, of course not, because it is not the strength of the pistons that makes the car faster, it is the compression, and it just so happens that the pistons need to be stronger in order to accommodate this increase in pressure. Engines are designed for a specific octane rating based on the amount of compression inside the cylinder- so if you use an octane rating other than what is recommended, it is pointless. Keep in mind however that using too low of an octane rating will damage your engine. Basically, if the octane rating you use is too low, you will experience knocking and will damage your engine. If you use an octane rating higher than needed, you are just throwing money away because the higher the rating the more expensive the gas.
 

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High octane fuels only help if you advance the timing on the bike or somehow change the compression ration to a higher ratio. I believe the the compression ratio on the '03s are 13:1 which would require 93 octane or higher. They did a test and found out that running 95 octane produced the best HP and optimum preformance for the bike. Anything less or more then that saw a SLIGHT degregation in power. If you increse the compression ratio you could get more power but would need a higher octane to prevent detonation or "knock" inside the engine. Also if you have the stock exhaust on your bike you will cause servere damage to it. You MUST have an aftermaket exhaust on the bike. that does not contain a catylitc converter. Because race fuels contain LEAD which will damage the CAT. But Leaded fuels will not hurt the engine of any motorcycle, and some people even believe that leaded fuel is actually better for sportbikes then unleaded. Something about the cylinder walls and seals. But if you are going to use race fuel first advance your timing and then I would recomment C-10 Race fuel which I think is around 108 octane.
 

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There are 3 ways of measuring octane..

1)Research octane(R/RON):
The octane as tested in a single cylinder octane test engine operated under less severe operating conitions. Affects low to medium speed knock and engine run-on.

2)Motor Octane(M/MON):
The octane as tested in a single cylinder octane test engine at more severe operating conditions. Affects high speed and part throttle knock and performance under load, passing, etc.

3)Pump Octane/Antiknock Index:
Combination of #1 and #2..A term used to describe the octane as posted on the retail gasoline dispenser as (R+M)/2. This is what we use to measure in the US/Canada.

In Austrilia, for example, they just use RON, so their #'s dont match ours in North America.

Here is a good write of of what octane does: http://www.howstuffworks.com/question90.htm
 

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California sucks! 91 octane = super unleaded. Maybe that is why I have always had a slight knock in my engine. Do any of you here in cali use any type of octane boost to counteract this tree hugger fuel that they force on us?
 

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I guess that it isnt really a knock .......... just a little more engine chattering than I am used to ......... haha or maybe because the stock exhaust is just too damn quiet. hahahaha!
 

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Sclong Maybe the area in which you live in is a higher alltitude then most of us at sea level. Cause it wouldn't make sense to not offer 92 or 93 octane if you needed it. the 92 or 93 octane gas dont pollute more. So Id like to think that your a little higher up and just dont need 92 or 93.
But damn Califonia SUCKS all your CRAP ASS regulations.
By the way vote for Arnold
 

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Yeah you are probably right .......... I think that 91oct is standard all across California. I am planning on riding home to Florida from Cali within the next two months so i will get to see what happens at different altitudes. I think that the altitude here is about 500 feet so it shouldnt be that significant.

The performance of the engine seems flawless, just a little chatter. Although i only have 800 miles on her so far. After she is fully broken in and I can go to synthetic, maybe that will quiet it down a tad. Some of the members here mentioned that on that taboo oil/engine break in topic that pops up on occasion. I will wait and see.

ARNOLD IS THE MAN!
 
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