[JAYSTENSEC4CYL]

The only thing octane tells you, Please listen to this, is a FUEL's ABILITY TO RESIST BEING LIGHT BY HEAT OR PRESSURE.

Thats it. It is not directly tied to power production, and for 100% sure more octane is NOT BETTER, and often times worse.

If you actually take the time to learn about fuel, and you should, you will find that with pump fuel you should always use the LEAST octane that does not knock or ping.

I would bet money that will be less than 93 octane on your bike. That sticker is there as a cover there ass sticker. They have no way to know what quality of fuel you will use, nor how you will use the bike. 93 most likely will not make the best power for the bike, but it will for sure keep ping at bay.

The good race fuel makers have very good RACE fuel in octanes from 87 on up. If you really test it you will find that the 100+ octane stuff, while possibly making more power than pump fuel, will make less power than a race fuel with a proper octane rating for your application.

You have a very small window in which to push down on the piston. Octane has a GREAT deal to do with this. It is important to use the correct octane if you want to make the best power and have the least ammount of engine deposits.

The 87 octane race fuels smell just as cool as the 100 octane stuff believe me, and they will work better in a stock compression sport bike.

I built an 07 G1K with N20 for a customer. It runs a 50 shot on stock compression. WE use MRX01 (98oct) when on spray as a saftey net. 98 oct is way way over kill for a stock compression bike with no power adder.

I built an 04 G1K with a bit over 14 to 1 compression once. It is the only engine I have built to date that pinged on pump gas. It had an overbore piston size which makes ping EASIER to acheive. That bike runs fine on 92 octane once we took a couple degrees of timing out of the low and midrange with an ignition module. See that way you still get the top end power you are after.

By using too high of an octane you are, in effect, retarding the timing across the entire rev range, and loosing power by doing it if you are not actually needing the octane to avoid ping or knock.

 

[JAYSTENSEC4CYL]

I should add VP's site has some great info about octane, as well as a list of their race fuels, their intended application, and their octane.

 

[JAYSTENSEC4CYL]

Higher octane gas does NOT have a slower flame propagation, NOR does it have less jewels of energy per unit volume than lower octane fuel. It only prevents early dentonation. In thermodynamics, the Ideal Gas Law states that, PV=nRT where P is pressure and T is temperature. Thus when pressure goes up (read high compression ratio), the temperature goes up and premature detonation is more likely. That is why high octance becomes necessary.

He's getting just as much or more power by running 100 octane vs. 91.

This is not true as I understand it. when dealing with pump gas, the lower octane fuel will have a quicker flame speed, as well as more BTU per gallon, ounce or whatever you want to use to measure it.

 

[JAYSTENSEC4CYL]

I will aslo mention that under about $15 a gallon and you are wasting money on race fuels. real race fuels cost real money.sad but true.

 

[JAYSTENSEC4CYL]

NOPE, ALL OF THAT IS INCORRECT.

I don't know of any moder jap liter bike that has a knock sensor.

It is a misconception to think that if it has high compression it NEEDS higher octane.

Motorcycles have several things going for them in the anti kock department that cars just don't have.

They have GREAT cylinder heads. They put the best factory cars to shame. They have all alloy motors that shed heat better than most car motors, the cylinders are MUCH smaller and thats very important, and motorcycles don't use as much of their total power just to move the vehicle.

They can have higher compression than cars but run on the same octane because of this.

Most every car has a knock sensor, most modern bikes do not because they simply do not need them yet.

ping and knock is MUCH less likely to happen at higher rpm than it is at mid to low rpm. Thats in cars, trucks, or bikes.

allot of people think this way. It's a common misconception. You don't need high octane. You don't need a certain octane, you need enough octane to keep it from pinging or knocking. Thats it. More is not better. It just costs more money, makes less power, and add's more engine deposits to the combustion chamber (which can require higher octane...lol)

 

[JAYSTENSEC4CYL]

take exception all you want, it's the plain truth.
It has nothing to do with economy, or performance or non performance engines. It's a simple matter of understanding engines.

weither it's performance oriented or not, you don't want the motor to ping. Thats terribly bad for an engine. So what you want to do is use the LEAST octane that does not kock or ping. That means it it pings on 87 then you try 89. If it stops pinging then thats your fuel choise. It's not complicated.

Most every modern bike I have dealt with runs fine on 87 octane if it's stock. Not all, but most.

I have built several engines for motorcycles now that have been between 13 to 1 and 13.5 to 1 and they all have run with out pinging on 87 octane pump fuel.

You won't be hearing ping at 175mph, as that would be topped out in 6th on your bike (and a speed you won't be seeing on Heartlands front straight, though it humored me) as like I said before you will get ping at lower and mid rpms first. Its very hard to miss.

at higher rpm there is just not time for the fuel to ping. At high load and lower rpm then you get ping. You have high cylinder pressure (which is pressure and heat) and the resistance of the tall gear at an non optimal rpm for aceleration.

If you want to use 91 octane then thats fine. You are welcome to do it.

Please wave hi to the G1K's that pass you, I might have built one of their motors When you get back in the pits, see what fuel they are using.

 

[JAYSTENSEC4CYL]

thanks man, you are AWESOME!!! LOL

I freaking missed the front rotors on EBAY!! I am an idiot. I got atacked by the demo version of GT5 on PS3 and I could not get away from it in time...lol

 

[JAYSTENSEC4CYL]

Well you have me there. I am not a thermal energy grad, not someone who uses big words when they talk about what they do not know.

in Dyno testing it has been proven that higher than needed octane makes LESS power.

My own experiance with fuels and motors has proven this to me.

If you honestly think that sticker says 91 octane because thats what the bike nees you just simply do not understand fuel, or manufacturing on a large scale.

I don't know thermo dynamics but I know late model bikes don't use knock sensors yet. I don't know thermal dynamics but I know most stock bikes will make more power and have better throttle response on 87 rather than 91. I don't know thermo dynamics, but I know you didn't see 175mph on Heartlands starightaway...lol

now clearly flame speed and octane are not locked together one to one. But from my understanding when you go to say Texaco their 87 will have a slightly quicker flame speed than their 91. Now thats not to say their 91 wont have a quicker flame speed than someone elses 87, but within that brand the lower octane is going to have a quicker flame speed than the higher octane PUMP fuel.

there is a big difference between PUMP fuels and race fuels.

There is better oil out there than what Yamaha puts in the bike. There is better brake fluid than what Yamaha use's. There is even better coolant than what yamaha uses. There are better tires than what they use from the factory, and better chains...etc you get the idea.

Yamaha reccomends what is SAFE for EVERYONE to use in their bikes no matter how you use it. Riding fast through your favorite canyon you are less likely to get ping than say riding up a long hill with your overweight girlfriend on the back in the middle of the summer in too low a gear.

The fuel you use is a timing tool as much as a heating element. You have a very small window to effectively push down on the piston.

It's really not amazingly hard to understand. Dyno your bike with 87 in it, then try it with 120oct. If it's a stock bike I can bet you money which will make more power The difference is much smaller between 87 and 93 but it is still there.

there is a certain octane you need to keep the motor from knocking. Once you have enough octane to keep it from knocking adding more octane is just a complet waste.

Octane is a measurment of a fuels ability to resist ping. That is the only thing the octane rating tells you. The way fuel is market and the typical american mentality is that more is better, but fuel like medicene more can hurt and not help.

 

[JAYSTENSEC4CYL]

lol, but no one ever believs me.

this has been talked about to death really.

The info is out there.

Go look on VP's site.

Look up how octane is actually tested, and what it tells you about a fuel. You do that and you will see how out dated and silly the testing method really is for what we are doing.

 

[JAYSTENSEC4CYL]

Preoldage Hair Death? Yep I have that...lmfao

 

[JAYSTENSEC4CYL]

Aron you looking to adopt? I have been looking for a good home for quite some time

Cool stuff for sure

BSR-1 I am a city boy, we don't need no stinking Post Hole Digger.

 

[JAYSTENSEC4CYL]

Brian it would be better to tune it on 87, but if it's tuned on 93 and you switch to 87 it is not going to hurt anything.

The difference in flame speed between 87 and 93 is fairly small and will not have any real world impact on a map for a street bike thats tuned to be safe.

Your 5 valve head on your yamaha, while having some advantages is one of the slowest burning heads in all of motorcycling. Stock from the factory the 98-03's have 55 degrees of total ignition advance. I assume, but do not know for sure, that the 04-06's are similar. Most other performance bikes run around 35 degrees.

If you run 13.5 to 1 or less it will run properly without ping on 87 is my guess. I know that may sound crazy to some, but thats been my experiance with other motors I have built.

Problem with the 5 valve head is the combustion chamber is very wide and very short. Thats not great for flame travel. raising the compression will make it shorter yet further hurting the flam speed, though the added compression will help it a bit.

every motor I have built so far I have run on 87 once it was done. Only one has ever pinged and required more octane and timing adjustments.

Motorcycle's have allot of advantages over cars in the ability to run less octane.It may go against common wisdom, but motors don't lie, they just do as they are told.

Now one thing I have noticed with several of the 04-06 R1's I have ridden is that they clatter when opening the throttle up from idle when in gear. No matter what pump fuel I have used they have done this, though not everyone I have ridden has done this. If I had to guess I would say it's a bit too lean, and has a bit too much ignition advance right off idle. I never have personally been able to play with one and see what richening up that area would do, or taking timing out of that area would do.

 

[JAYSTENSEC4CYL]

I said, as I understand it, that a stations 87 oct will have a slightly faster flame speed than it's own 93. I also stated that those flame speeds might be higher or lower than 87 or 93 from another source. This is what i understand to be true of PUMP fuels.

Race fuels are a whole different animal, and the fuel makers have the ability to change many things about a fuels property, including octane and flame speed.

Octane is not the only thing thats sets the limit of detonation, but for a street bike running on pump fuel it is the most significant.

I can tell you from my own experiance, in my 00 R1 ever since I have learned a bit about octane and fuel, I have run nothing but 87 octane in it. Not one problem. No knock, no ping.

 

[JAYSTENSEC4CYL]

Sanaja when I was talking about pump fuels I was referring to Pump Octane number. It will be on a little sticker that says (R+M/2).

 

[JAYSTENSEC4CYL]

Those guys are very smart

I think they said several things that I have also said, as well as backing up some of the things R1 said.

 

[JAYSTENSEC4CYL]

Sanaja, I would use the least that did not knock or ping.

One of the links posted said that people don't understand that octane is a chemicl property, and often try to tie in a physical property to it to make it more understandable for them, though that understand would then be wrong.

I think I am guilty of this as well.

I still understand a certain companys PUMP gas to have slower flame speeds in the higher octane fuels than the lower ones, though now I understand that if this is so it's not tied to octane, but rather is that way because the fuel makers wanted it that way.

 

[JAYSTENSEC4CYL]

That quote messed me up too. Shit's deep. that was one of those things you read and you stop and ponder.

I did not write that very well

The link said that octane is a chemical property of a fuel. Most people, like myself, have a hard time grasping a chemical property, and so try to relate it to a physical property to understand it. But in doing that, stating a chemical peoperty as a physical property, they are showing that they do NOT understand the chemical property.

I believe this is exactly what i was doing, and exactly what R1 was trying to tell me though i was too stubborn to listen.

I believe everything I have said about what octane to run is correct, and still believe that one makers fuel will have more BTU and quicker flame speed in their 87 than in their 93, but I see now that it has nothing to do with the octane, but rather they are traits that the fuel maker built into the fuel for whatever reason.

I could be wrong on that point as well, though in the real world it makes no pratical difference.

You still want to run the least octane that does not ping or knock. Thats in your bike, your lawn mower, and in your car and truck. Though, and this is important, it is MUCH more confusing with your car or truck as they will have a knock sensor.

You won't hear the knock or ping if you use too low an octane, as the car will back off the ignition timing to cope with the shit gas you just used. You will though if you are paying attention see that it has less performance, and gets worse MPG.

 

[JAYSTENSEC4CYL]

But then you can confuse people again by telling them that if you have two identical heads, except one is aluminium and the other is iron, the iron head engine will make more power on a dyno.

I have heard of this before, but never understood why? Is the alloy heat stealing power by sheading heat so quickly?

 

[JAYSTENSEC4CYL]

that is simply incorrect. They make "race" fuels in 87 octane just for stock motors.

 

[JAYSTENSEC4CYL]

also the race fuel is much more consistant and leaves less engine deposits.