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High octane

Rob S.

Rob S.

Forum Guru
Past Site Supporter
Like so many others, I waste money buying premium fuel for my 1982 GS1100e (stock except for pods and pipe, 9.5:1). I always thought it was just extra, (if unneeded) protection against detonation.

Now I've just read this recent post:

"Since higher-octane "premium" fuel burns slower, you need to advance the timing several degrees to get it to complete its burn in time.
With stock timing and "premium" fuel, the mixture is not being completely burned, robbing you of power.
My suggestion here is to go with the factory-recommended "regular" fuel."

Thoughts, comments? Gas money doesn't concern me, but "robbing you of power" certainly caught my eye. The above quote may be taken out of context, but it implies a bike would make more power with regular gas.

Any truth in that?
 
rob you are not loosing any power.
going from 86 to 93 octane IMO does not change your seat of the pants feel.
now if you buy "racing" gas aka 100 octane and up and if it's not needed it can take power away but....it smells sooooooooooo good :D
 
I've never used 86, always 92 or 93.

So theoretically, I could gain a miniscule amount of power by switching from 92 to 85?

What would you put in a relatively stock 1100EZ if you didn't pay for gas?
 
Higher octane fuel is "harder" to burn than lower octane. In engines with high compression ratios, low octane fuel may explode prematurely. Using higher octane fuel prevents the premature burning (knocking).

I'm not entirely sure that it burns slower, but higher octane fuel can withstand higher compression without igniting.

Read this:
https://en.m.wikipedia.org/wiki/Octane_rating
 
I've always believed that if you didn't hear any knocking with regular, premium was just a waste of money. Since I don't pay for gas, I always got premium. But if I'll theoretically gain a teensy amount of power with regular...

I might as well save someone a few pennies. Make my accountant proud.
 
you never really know what's coming out of the hose honestly...
i would just do as you have been doing but that's just my opinion.
 
IMO premium fuel is a ripoff anyway. Most people don't know what octane does anyway, they think high octane fuel makes their ride faster (it doesn't). High octane fuel just prevents detonation in forced induction or high compression engines.
 
In hot waether my 1150 will ping if I try to get away with even mid grade. Mainly under load, or a quick roll on the throttle, if passing for instance.
 
If your engine pings, knocks or detonates, try a higher grade. If it doesn't don't. Almost all of my GSes have been fine without it, a few have pinged once in a while in hot weather, so on that one I used better grade in Summertime. One of my buddy's GKs detonated constantly once warmed up, but it had something wrong with it, the Premium fuel didn't help it much if any. A big waste if it's not needed, and I believe it does lose a bit of power if the engine is built for, tuned for and runs fine on regular gas. I'm also quite sure any power losses are much to small to check with any butt dyno. And on an engine with a problem such as carboned up combustion chambers or advanced timing among others higer octane fuel can be an effective band-aid.
 
Gasoline companies do have "winter blends" and "summer blends" too. The fuel you get in the winter is not the same fuel as you get in the summer, even if it's the same exact pump with the same octane rating.
 
srg said:
Gasoline companies do have "winter blends" and "summer blends" too. The fuel you get in the winter is not the same fuel as you get in the summer, even if it's the same exact pump with the same octane rating.
Click to expand...

That was the case some years ago, though not sure it is now. The winter mixtures were ones with ethanol blended in, and switched in the summer to non blended gas. Now that 10% ethanol is in everything all the time, not sure we have those season blends anymore per se.
 
I've also read that it takes a gallon or so of the previously pumped fuel to move through the pump & hoses before you start getting your premium fuel. Not a big deal for most vehicles that might take on 15 gallons, but for a bike, a different story. Buying five bucks of premium might get you pretty much what you'd get if you bought regular.

So, if you purchase premium, the next person to use that pump gets a gallon (or so) of premium for the price of regular.
 
My GS would knock continuously on 87 octane. On 91, only once in a while. on 93, never.
Made for tough times on rallies when we stopped in tiny hamlets where only 87 was available.
 
My 82 GS1100 would ping in very hot weather. Ethanol worked better than regular, but still got a little ping if it was hot weather. I got in the habit of using a station that sold "Turbo Blue" racing fuel. I put in one gallon and topped the tank off with regular. The pinging was history. Did it for years.
 
If its at all possible I use the alcohol free premium they have here in Montana. Not because of the octane but because of what the alcohol does to the carbs
 
Not to turn this into a pods vs not thread, but ive often wondered what affect the pods sucking in hot air from directly behind the cylinders has, If any, on detonation......
 
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