Sportbike World banner

1 - 20 of 23 Posts

·
Registered
Joined
·
17 Posts
Discussion Starter #1
Just bought 99 R6 was wondering which octane of gas I should run? I bought a clymer manual and its says use 87octane. Should I stick with the manual or run high octane like 93-94?
 

·
Registered
Joined
·
2,904 Posts
run 93. You can run 87 and up, but when you use gas with that low octane, you may damage the engine/spark plugs what not only if you do fast accelerations and rev really high. You could get away with it, but since its a motorcycle, I wouldn't worry about gas milage, just use 93.
 

·
Registered
Joined
·
609 Posts
I'm not following you guys.

From what I understand, if the manual calls for 87, you're wasting your money using a higher octane.

Higher octane doesn't necessarily = more performance or better for the engine if it's not required.
 

·
Registered
Joined
·
17 Posts
Discussion Starter #6
I fully agree but with a motorcycle that might run at high rpm's dont you think the higher the cleaner.
 

·
Registered
Joined
·
50 Posts
octane

i kinda agree with that statement, but....
i know in cars if it calls for 87 you better use 87. there are certain things like timing and stuff that the computer is set to run with a certain octane. although you might just be messing with your air/fuel mix. i dunno. follow your mom. if it says 87 or higher run 93 or 94, but if it only says 87, follow that. ultimately you'll know what to use by how your bike runs. hope this gave you some different opinions cause my bike says 91 OR higher. later. go see a dude named martinez on third street he can hook you up.
 

·
Registered
Joined
·
2,904 Posts
With high reving engines of modern sports bikes, low octane fuel can cause lots of engine nocks/pings. This is caused because of the gas sprayed into the cyclinder is not burning in the correct area (when the piston is all the way up, where max compression is). The gas, depending on the octane, would prematurely dedinate. This is because the higher the octane, the slower it burns so in high compression engines, the gasoline will not light up until it hits the correct compression and ignited by the spark plugs.

What's wrong with premature dedination? Well this can cause engine wear and damage. Because the premature dedination causes the gas to burn, which turns the oxygen and liquid gas thats sprayed in there from either carbs or injectors into carbon monoxide in the form of gas of which pushes the cyclinder back down to its fully extended state. Since the expanding pressure of the CO is formed before the piston reaches its max compression it causes extra force in the opposite direction on the pistol and the connecting rod. This causes stress on the metal and lead to microfissures (small cracks) and could end up reducing the life span of the engine.
 

·
Registered
Joined
·
50 Posts
so the lower the octane the lower ignition temp? but what about all this stuff that people say about their engines knocking, then thay increase octane and it stops. great info though. nice to hear technical explainations instead of opinions. thanx.
 

·
Registered
Joined
·
6,400 Posts
Since way back in '46 & right up to Autumn of '05 I have used 87 octane in my '97 Yamaha YZF 600r, '00 Honda 929 & '03 Honda 954.

I have tried 91 to 93 & the bikes perform the same, do not run cooler, do not give better milage, & besides we have had this discussion before & before & before. It seems to be those new to riding that feel they must use 93 octane. Yes I have seen those with cruisers to HD bikes to old regular riding position bikes filling up with 91 octane as that is basically the highest we canobtain here in Cdn. Yet my older to more modern bikes only require 87 octane.

Look in your MOM & you will find the makers have posted out what should be used.
 

·
Registered
Joined
·
892 Posts
yes this topic has been beaten to death i think. i just use mid grade, so i get the best of both worlds :)
 

·
Registered
Joined
·
2,904 Posts
I'm not exactly sure if the lower octane amount in gasoline would yield a lower ignition temp. I believe that gasoline (no matter the octane number) will burn at the same temp (+/- a few degrees). I just know that the resistance for ignition due to compression is lowered when using higher octane fuel. Or was it the other way around? damnit, I need sleep I can't think!
 

·
Registered
Joined
·
447 Posts
jbaz is rite about the burn time of 93 compared to 87. if you can run 87 and have no pinging run it , if you start hearing the engine ping try 91 or 93 and see what your bike runs best on. when you start modifing these bikes like exhaust and mapping/ jetting it will change things and a bike that runs good on 87 before may start pinging after that. my 954 runs best on 93 i tried 87 and it pinged bad but on 93 no pinging but i have a few mods also, but my 02 montero sport hates 93 and runs best on 87.
 

·
Registered
Joined
·
414 Posts
If you can hear pinging you have some major detonation issues. Most engine misfires (detonations, pinging) can not be heard. If you can physically hear the detonation, that sound is the equivalent to hitting the piston with a hammer. Believe it or not, in a spark ignition engine the burn process of the air/fuel mixture is actually a controlled burn NOT an explosion like most people refer to it. When you have detonation (aka Pinging) it is an actual explosion and not a conrolled burn like it is supposed to be. the lower the octane the fuel the more volatile it is, this means it will ignite easier. In a 4 cycles engine you have exactly that, 4 cycles. These cycles are intake, compression, power, and exhaust. Pinging occurrs at the end of the compression stroke. When an air/fuel mixture gets compressed the fuel and air atomize and ignite easier. In a high compression engine the air/fuel mixture is obviously compressed more than a lower compression engine. Therefore, when using a lower octane gas (More volatile) in a high compression engine the air/fuel mixture will rapidly explode instead of burn, this is what creates the detonation. Severe detonation can result in bent connecting rods, and holes burned through the top of the piston. High compression isn't the only factor that plays a role in what octane to use eventhough it is the biggest reason for detonation. It may also depend on Valve timing, ignition timing, RPM, etc. Higher octane fuel will decrase the chance of detonation, but will not give you more power or gas mileage. If the manual says use 87 you could most likely get away with it or you could play it safer and go with 89, or even go with 100 octane if you really wanted to. Anything that is higher octane than what is needed is just a waste of $$$. In a motorcycle it is not a huge deal because you do not use that much fuel. I would just use what the manual says unless you have your engine modified. Changine the fuel curve with a power commander (if fuel injected), changing the jetting of the carb, changing ignition or cam timing, etc. will change what octane you need. Especially ignition timing. Advanced ignition timing need higher octane fuel. As I have said, Just use what the manual recommends or higher (never lower octane). I doubt a major motorcycle manufacturer would mislead you because they wouldnt want broken bikes with engine problems going back to the dealer for warranty work.
 

·
Registered
Joined
·
376 Posts
my owner's manual says 91 minimum, but that's for the California model, so if I lived somewhere else I imagine I could use a lower grade, I don't know.
 

·
Super Moderator
Joined
·
704 Posts
wheelie_steve said:
If you can hear pinging you have some major detonation issues. Most engine misfires (detonations, pinging) can not be heard. If you can physically hear the detonation, that sound is the equivalent to hitting the piston with a hammer. Believe it or not, in a spark ignition engine the burn process of the air/fuel mixture is actually a controlled burn NOT an explosion like most people refer to it. When you have detonation (aka Pinging) it is an actual explosion and not a conrolled burn like it is supposed to be. the lower the octane the fuel the more volatile it is, this means it will ignite easier. In a 4 cycles engine you have exactly that, 4 cycles. These cycles are intake, compression, power, and exhaust. Pinging occurrs at the end of the compression stroke. When an air/fuel mixture gets compressed the fuel and air atomize and ignite easier. In a high compression engine the air/fuel mixture is obviously compressed more than a lower compression engine. Therefore, when using a lower octane gas (More volatile) in a high compression engine the air/fuel mixture will rapidly explode instead of burn, this is what creates the detonation. Severe detonation can result in bent connecting rods, and holes burned through the top of the piston. High compression isn't the only factor that plays a role in what octane to use eventhough it is the biggest reason for detonation. It may also depend on Valve timing, ignition timing, RPM, etc. Higher octane fuel will decrase the chance of detonation, but will not give you more power or gas mileage. If the manual says use 87 you could most likely get away with it or you could play it safer and go with 89, or even go with 100 octane if you really wanted to. Anything that is higher octane than what is needed is just a waste of $$$. In a motorcycle it is not a huge deal because you do not use that much fuel. I would just use what the manual says unless you have your engine modified. Changine the fuel curve with a power commander (if fuel injected), changing the jetting of the carb, changing ignition or cam timing, etc. will change what octane you need. Especially ignition timing. Advanced ignition timing need higher octane fuel. As I have said, Just use what the manual recommends or higher (never lower octane). I doubt a major motorcycle manufacturer would mislead you because they wouldnt want broken bikes with engine problems going back to the dealer for warranty work.
This reply should be stickied to the front and everyone who asks the question forced to read it first! I've listened to the argument for years. The above is the best advice.
 
1 - 20 of 23 Posts
Top