Fuel octane explained.

[BajaRon]

A little bit of Apples and Oranges here because the author is referencing an air cooled Harley, for the majority of his information.

The Spyder and Ryker are much different animals. Yes, premium fuel, especially in warm to hot conditions, or when heavily loaded or running hard, is the best for our rides. But you can get away with mid grade or even regular without any danger to your engine. This is because the ECM (Electronic Control Module) or the 'Brain' monitors conditions and will not allow the pre-ignition that low grade fuels can cause (as referenced in the article). Uncontrolled, you can actually blow a hole in your piston. But the Spyder/Ryker takes all that out of the equation by retarding ignition, preventing this condition. You will lose some power and fuel mileage. But the process is seamless. And unless you are paying attention, you probably won't notice. This is why you hear riders say they run regular fuel all year long and find no difference.

Don't try this in an air cooled or non-computer controlled machine or you may experience some catastrophic results. But for our rides. It's not dangerous.

[UtahPete]

Very good information...that's why I tuned the ECU (Stage II)...so the bike no longer runs lean on fuel... And...add an octane booster...boosting from 91 to 95 octane...those two things made a big difference in performance.

I concur. The interesting thing is I seem to get better mileage, even though the mix is richer.

[Knizar]

A little bit of Apples and Oranges here because the author is referencing an air cooled Harley, for the majority of his information.

The Spyder and Ryker are much different animals. Yes, premium fuel, especially in warm to hot conditions, or when heavily loaded or running hard, is the best for our rides. But you can get away with mid grade or even regular without any danger to your engine. This is because the ECM (Electronic Control Module) or the 'Brain' monitors conditions and will not allow the pre-ignition that low grade fuels can cause (as referenced in the article). Uncontrolled, you can actually blow a hole in your piston. But the Spyder/Ryker takes all that out of the equation by retarding ignition, preventing this condition. You will lose some power and fuel mileage. But the process is seamless. And unless you are paying attention, you probably won't notice. This is why you hear riders say they run regular fuel all year long and find no difference.

Don't try this in an air cooled or non-computer controlled machine or you may experience some catastrophic results. But for our rides. It's not dangerous.

This is what I like too hear! I run 87 grade, never over loaded or working my Spyder very hard. 20K miles and no problems so far. Hope to continue doing the same. My dealer said it was OK, and now that "Baja Ron" seconded it!

.........Bill

[BLUEKNIGHT911]

A little bit of Apples and Oranges here because the author is referencing an air cooled Harley, for the majority of his information.

The Spyder and Ryker are much different animals. Yes, premium fuel, especially in warm to hot conditions, or when heavily loaded or running hard, is the best for our rides. But you can get away with mid grade or even regular without any danger to your engine. This is because the ECM (Electronic Control Module) or the 'Brain' monitors conditions and will not allow the pre-ignition that low grade fuels can cause (as referenced in the article). Uncontrolled, you can actually blow a hole in your piston. But the Spyder/Ryker takes all that out of the equation by retarding ignition, preventing this condition. You will lose some power and fuel mileage. But the process is seamless. And unless you are paying attention, you probably won't notice. This is why you hear riders say they run regular fuel all year long and find no difference.

Don't try this in an air cooled or non-computer controlled machine or you may experience some catastrophic results. But for our rides. It's not dangerous.

Thank you Ron for pointing this out Knowledge is power ..... however a LITTLE knowledge can cause issues ..... I trust the ability of the ECU to allow me to use REG w/ethyl ....ALL the time .... So 0ver 77,000 mi. without issues .... JMHO .... Mike

[2dogs]

In layman's terms, it is called a knock sensor, or antiknock sensor. But if you hear that sound of marbles being dropped into a tin can, get off the throttle buddy, or you're going to pop a piston. Ron is spot on. But remember a dirty cylinder with carbon build up, and a little chunk left glowing from the previous combustion, is something the ECU may not be able to overcompensate for. So don't use junk fuel or too many additives. Treat your spyder like you love her, TLC, and she will give you what you want.

[BajaRon]

I concur. The interesting thing is I seem to get better mileage, even though the mix is richer.

Not surprised. The lean mix on modern ICE is for emissions, not for peak power or efficiency. A correctly enriched fuel mix can give you both more power and fuel mileage while at the same time your engine runs cooler. In my VW TDi I went from 36 mpg to 45 mpg with noticeably more power. That's what I'm talking about!

[2dogs]

I concur. The interesting thing is I seem to get better mileage, even though the mix is richer.

Interesting that some of us SL's noticed that. I notice that more so when I ride 2up and don't drive like a hooligan.

[Woodenfish]

Not surprised. The lean mix on modern ICE is for emissions, not for peak power or efficiency. A correctly enriched fuel mix can give you both more power and fuel mileage while at the same time your engine runs cooler. In my VW TDi I went from 36 mpg to 45 mpg with noticeably more power. That's what I'm talking about!

What did you do to obtain a 128% increase in your fuel economy?

[BajaRon]

What did you do to obtain a 128% increase in your fuel economy?

Malone Tune on the ECU and Rawtec Exhaust. Increased Wheel HP by 35 and Wheel Torque by 65. Very noticeable. So, you end up going further on the same amount of fuel. Actually, these things don't give the engine anything. They just restore what was already there.

[Peteoz]

What did you do to obtain a 128% increase in your fuel economy?

128% increase, Woodenfish? Surely that would have meant going from 36mpg to around 80mpg? ……unless the US uses different % calcs, wouldn’t 36mpg-45mpg be around a 25% increase, which is quite feasible ?

Pete

[Woodenfish]

128% increase, Woodenfish? Surely that would have meant going from 36mpg to around 80mpg? ……unless the US uses different % calcs, wouldn’t 36mpg-45mpg be around a 25% increase, which is quite feasible ?

Pete

Thank you Pete. I don’t know how I typed that “1” in and didn’t catch it. It should read 28% increase in fuel economy.

[2dogs]

Thank you Pete. I don’t know how I typed that “1” in and didn’t catch it. It should read 28% increase in fuel economy.

Smooth move Woodenfish. You had me on my dam cellphone calculator for 15 minutes trying to figure out how you came up with 128%. I even googled Ron's VW TDI searching for the secret engine mod that would produce that increase. But I guess I just get easily sidetracked.

[BajaRon]

Smooth move Woodenfish. You had me on my dam cellphone calculator for 15 minutes trying to figure out how you came up with 128%. I even googled Ron's VW TDI searching for the secret engine mod that would produce that increase. But I guess I just get easily sidetracked.

I was going to say something in my original reply. But for whatever reason, I decided against it. I figured someone else could pull that pin for me...

[2dogs]

I was going to say something in my original reply. But for whatever reason, I decided against it. I figured someone else could pull that pin for me...

Like on this site and many others, all you have to do is wait a few minutes and someone sooner or later will jump in with the obvious.

[Raven]

All I know is my Harley (XR1200) runs better on 91octane than on 94.
This bike dyno's close to 90 hp at the back wheel.

[BajaRon]

All I know is my Harley (XR1200) runs better on 91octane than on 94.
This bike dyno's close to 90 hp at the back wheel.

Could be you would need to advance the timing to realize any improvement with the higher octane. It is not water cooled, which is usually better for pushing timing adjustments. But the oil cooling is supposed to be very good. So maybe that would work.

[SLICE]

https://www.youtube.com/watch?v=z_IV...annel=RevZilla

Flame away.

[EdMat]

No need to flame on that link. Much better than most on the subject.

[vito1943]

I'm not an engineer. I respect those that designed my RT and if they say that I should use 91 or higher octane, that's good enough for me. My Spyder is a toy for my pleasure. I could have bought a far less expensive little motorcycle if the cost of fuel was my main concern, or I could just ride my Honda PCX150 scooter which gets 100 mpg. Buying premium gas seems prudent and worthwhile to me. I keep a bottle of octane booster in my frunk just in case I ever end up at a gas station that does not sell the right octane that I need.

[190243]

Before Spyders are made electric we have to deal with gasoline. It's dirty, it smells and it's way too complicated. I never liked chemistry anyway.
I've seen too many erroenous threads and posts here to remain quiet, so here's everything you need to know about "Premium" vs "Regular" gas and which one is right for you.

Long Story Short (very simplified):

1. Modern Spyders run on Premium Gas, or for USA: octane rating of 91 (it's different in every country).
Here's from the owners manual: "Use premium unleaded gasoline with an AKI (RON+MON)/2 octane rating of 91, or an RON octane rating of 95". (See your owner's manual)
Yes, you can run your Spyder on lower octane fuels, but it comes at a cost (see #4)

2. This has nothing to do with how one grade burns hotter than another (it's the same), or how "Premium" is better than "Regular" (it's not)

3. The ONLY reason for this octane requirement is the engine compression ratio. That's it. Nothing more, nothing less. It's all about compression. Simple physics and chemistry.
Higher octane fuels resist to self-combustion due to the heat of the compression. The higher the engine compression, the higher the requirement for octane. Spyder engines have a very high compression ratio (12.2:1 for twins and 12:1 for triples) Any engine with compression over 11:1 has to have a "Premium" gas.
NOTE: I only looked up compression of modern Rotax engines. Yours might be different.

4. To those who run on "Regular" gas: your engine will knock. Here's what you need to know: "Burning fuel with a lower octane rating than that for which the engine is designed often results in a reduction of power output and efficiency. Many modern engines are equipped with a knock sensor (a small piezoelectric microphone), which sends a signal to the engine control unit, which in turn retards the ignition timing when detonation is detected. Retarding the ignition timing reduces the tendency of the fuel-air mixture to detonate, but also reduces power output and fuel efficiency."

5. "Premium", "Supreme", "Plus" and "Regular" terms are completely bogus and misleading. It's all the same gasoline. In fact, most of the gas stations use the same refineries. The difference is in additives. In simple terms: higher octane gas has more expensive additives and lower octane has cheaper additives. "Plus" grade gas is just a mixture of "Regular" and "Premium".

6. A more expensive, high octane fuel does absolutely nothing for the engine designed to run on lower octane fuels, however, a low octane fuel will damage or degrade performance and fuel economy of the engine designed to run on a high octane fuel.

If you want to know more, here's a good video: https://youtu.be/WYlk9C1o0nk
(I'm not affiliated with them in any way)

I hope this helps

when I’m in the states I use at least 91 cause your gas is crap. Lol

[IdahoMtnSpyder]

His explanation of why using an higher octane is not beneficial is good. That is pretty much agreed to by all on this forum. But he somewhat glosses over why you shouldn't use a lower octane. It is as he says, to prevent pre-detonation, or pinging. What he doesn't discuss is what causes pre-detonation. There are several different causes for pinging, but all of them are characteristics in the combustion chamber that stay hot enough to ignite the fuel mixture before the proper spark moment. Some can be things like sharp corners that don't cool down enough between firings.

What I contend is the Rotax engineers have done a d*** good job of designing the combustion chamber to prevent hot spots being present and causing pre-detonation. If you don't have a source to cause pre-detonation, then you don't need to have a pre-det preventative in place. Except the engine has been designed to make appropriate adjustments to ignition timing and fuel/air mixture to mitigate pinging, if the sensors detect it happening.

In the 9 years I have been on this forum there has not been a single post from an owner who has had engine damage caused by pinging from using 87 octane gasoline. My experience a few years ago showed my gas mileage was a touch better when using 87 octane vs 91 octane. Why? I can't explain it.

[UtahPete]

I'm not an engineer. I respect those that designed my RT and if they say that I should use 91 or higher octane, that's good enough for me. My Spyder is a toy for my pleasure. I could have bought a far less expensive little motorcycle if the cost of fuel was my main concern, or I could just ride my Honda PCX150 scooter which gets 100 mpg. Buying premium gas seems prudent and worthwhile to me. I keep a bottle of octane booster in my frunk just in case I ever end up at a gas station that does not sell the right octane that I need.

[BLUEKNIGHT911]

His explanation of why using an higher octane is not beneficial is good. That is pretty much agreed to by all on this forum. But he somewhat glosses over why you shouldn't use a lower octane. It is as he says, to prevent pre-detonation, or pinging. What he doesn't discuss is what causes pre-detonation. There are several different causes for pinging, but all of them are characteristics in the combustion chamber that stay hot enough to ignite the fuel mixture before the proper spark moment. Some can be things like sharp corners that don't cool down enough between firings.

What I contend is the Rotax engineers have done a d*** good job of designing the combustion chamber to prevent hot spots being present and causing pre-detonation. If you don't have a source to cause pre-detonation, then you don't need to have a pre-det preventative in place. Except the engine has been designed to make appropriate adjustments to ignition timing and fuel/air mixture to mitigate pinging, if the sensors detect it happening.

In the 9 years I have been on this forum there has not been a single post from an owner who has had engine damage caused by pinging from using 87 octane gasoline. My experience a few years ago showed my gas mileage was a touch better when using 87 octane vs 91 octane. Why? I can't explain it.

IMS ....you get it, I get it ... and some folks won't EVER get it .... Thanks for the explanation ..... Mike