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Octane rating you use?

  • Thread starter Thread starter Anonymous
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Anonymous

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I'm just curious as to what octane you guys are running in your GS's and why. Is it a personal preference, or some performance mod that requires it? When I first got my '79 GS750L, I always put 92 octane in and my father in-law was saying it didn't need it, use 87 only, etc. etc. What do you guys think?
 
Since most unleaded available these days has cleaners that's not an issue. I've always heard to use the lowest octane needed to prevent pinging. Higher octane gas means it has detonation inhibitors to slow combustion and reduce/eliminate pinging. I've also heard that using 92 octane in an engine that will run on 87 will speed up the carbonization process. My GS450 runs the same on any octane so I usually run 87. Once in a while I will run 89 or 92 if I will be riding on a very hot day or in a lot of stop n go.
 
The rule of thumb is if the GS is stock with no added ignition advance, then 87 octane is fine. That's normally what I use in my stock GS850, and I haven't had any problems.

I will confess that I sometimes put in 89 if it's really hot and I'm riding really fast, but I've never heard or felt any pinging or seen any indication that it's needed or does the slightest bit of good or bad.

Modified bikes that use more ignition advance and/or higher compression often need higher octane.

93 won't really hurt anything, in a stock GS, either. And against the cost of tires, stators, regulators, o-rings, and insurance, it's an incredibly minor part of the cost of riding. If it really makes you feel better, go ahead and fill up with 93.
 
Most GS's were designed to run on 87 octane. There is no benefit to using a highter octane than factory recommendation. Factory spec for my 1150 is 89 octane, so thast what I use.

Earl
 
I had a little pinging under load on hills so I use 93. I think it starts better and runs better but that is only my opinion. It only costs 80 cents more a tank.

Higher octane has a little bit longer shelf life than the cheap stuff. If you are not riding the bike much it is probably a good idea to use hi-test.
 
When I have a choice I get the highest octane I can. My 850 will ping under load in the heat. Since predetonation can really tear up an engine in short order, I look at the cost difference as just a small insurance premium to protect my investment. For most straight and level riding it is probably not needed, but the little additional security is worth it to me. I'm not fanatical about it; if I am out in the boonies and the one pump general store only has regular, I don't get bent out of shape.

I have also observed that I tend to get slightly better mileage with premium gas which partially offsets the addit cost. I seem to get my longest range on a tank when I pump Shell high octane.
 
Harley

Harley

When I had my last Harley, I received a service bulletin advising that low octane should be used. The reason they gave was this: They said alcohol is usually used to boost octane these days since all gas is unleaded. Further, they said alcohol is hard on the seals. :cry:

Whether that's applicable to our bikes, I don't know. I do think those Harley dudes are a pretty smart bunch and wouldn't have gone to the trouble to send out the directive is there wasn't something to it. :?
 
Re: Harley

Re: Harley

chuckycheese said:
When I had my last Harley, I received a service bulletin advising that low octane should be used. The reason they gave was this: They said alcohol is usually used to boost octane these days since all gas is unleaded. Further, they said alcohol is hard on the seals. :cry:

Whether that's applicable to our bikes, I don't know. I do think those Harley dudes are a pretty smart bunch and wouldn't have gone to the trouble to send out the directive is there wasn't something to it. :?
Click to expand...

Ethanol is used in al grades in certain parts of the country to reduce emissions and if the congress gets it's way it will be used in very area. MTBE is used in some areas but there is opposition ( mostly from ADM and the grain lobby) to using MTBE because of ground water contamination.

Alcohol based fuels are hard on rubber parts and also contribute to rust in the exhaust system as water vapor is released when alcohol is burned. gasohol also evaporates quicker than alcohol free fuel and we all know what that means.
 
Thanks for the input guys. Up here in MN, they put ethanol in all our gas, to make all the corn growers in the state happy. As it's been getting hotter here, I started running 92 octane, and haven't noticed any real differences, but we'll see what I get on mileage.
 
I found that my EZ was pinging under load running 87, so I switched to 89. It's better now. I checked the timing too, it's spot on. 8)
 
The recommended minimum 87 octane works for me. If I faced stop-and-go summer driving conditions I'd move up to 89 octane.

I avoid ethanol for my bikes because they are stored seasonally, and ethanol (alcohol) has an affinity for water that could contribute to rusting gas tanks.

In my cars, I seek out ethanol for its environmental benefits.
 
ARCO premium 92 for my 1150. I notice a tiny bit of pinging if I run anything less, especially when I'm in the mountains (6,000 ft. and up). And like dpep, noticeably better gas mileage.
 
renobruce said:
ARCO premium 92 for my 1150. ...And like dpep, noticeably better gas mileage.
Click to expand...

There is no science I've heard of that supports getting noticeably better mileage by using premium fuels. 87 octane gasoline has the same potential energy as 92 octane, and gives up that energy easier. The technical reading I've done indicated that using high octane gasoline in simple engines designed for 87 octane fuel provides less power and lower mpg.
 
dietcokeking said:
renobruce said:
ARCO premium 92 for my 1150. ...And like dpep, noticeably better gas mileage.
Click to expand...

There is no science I've heard of that supports getting noticeably better mileage by using premium fuels. 87 octane gasoline has the same potential energy as 92 octane, and gives up that energy easier. The technical reading I've done indicated that using high octane gasoline in simple engines designed for 87 octane fuel provides less power and lower mpg.
Click to expand...
I make no claims for any motorcycles other than my own. I arrived at my conclusion over years of trial and error (116,000 miles) on my 850. I always reset my odometer to 0 when I fill up with gas, so it is a simple matter to divide the mileage showing by the gallons purchased showing on the pump. I do it in my head without even thinking about it every time I get gas; it is just part of the fill up. I also try to factor in the kind of driving and driving conditions for each tank. The best comparisons obviously are when you are on a trip traveling pretty much at the same speed at the same elevation and temperature. Fillups with higher octane gas tends to mean more miles on the odometer when I have to stop for my next tank.

On occasions when I have noted better than my average mileage, it has more often than not been on a tank with the Shell brand high octane. I don't work for them or anything. That is just what I have obverved. I have no great love of the oil companies; if my experience had been otherwise I would not mind giving them less of my money.
 
dietcokeking said:
renobruce said:
ARCO premium 92 for my 1150. ...And like dpep, noticeably better gas mileage.
Click to expand...

There is no science I've heard of that supports getting noticeably better mileage by using premium fuels. 87 octane gasoline has the same potential energy as 92 octane, and gives up that energy easier. The technical reading I've done indicated that using high octane gasoline in simple engines designed for 87 octane fuel provides less power and lower mpg.
Click to expand...

If you get better mileage or more power from using higher octane it means you were getting some pinging, whether you were able to hear it or not. And yes it's possible to have it and not hear it. I'm all for results, wether there's any science behind them or not.

Still I find the 750 runs fine on 87 most of the time, with the seemingly usual exception of hot weather and hard riding combined. The 550 absolutely never complains about 87 octane. I'd say that depending on your usual riding conditions it could prove beneficial to raise the fuel octane used in your 750.
 
Up here in Canada you can get as high as 94 octane, but generally for my '84 GS750EF which has fairly high compression I stick around the 90-91 octane mark. In my "official" shop manual it recomends 90 or higher. I have used 89 and in hot weather, or stop and go traffic, I can feel it pinging ever so slightly but its still very drivable. If I use around the 90-91 stuff the pinging goes away in stop and go and hot weather. I have used the 94 stuff but it didn't give me any more power or smoothness so I stuck with the slightly lesser grade. In colder weather I sometimes go to 89 octane to help the bike along a bit because it rarely warms up to full operating temperature near wintertime. If it is hot summer driving an extra octane level won't break the bank and will give you a bit of insurance in case your stuck in stop and go traffic. Especially on air/oil cooled bikes.
 
Thanks everybody. I certainly learned something from this thread. -Pete '80 1100L
 
Me too. :D I never hurts to ask. And actually, It's been warmer up here lately, and I started running 92, and there's been a noticable difference in power and mileage.
 
IGlenn, what part of the Land of 10,000 lakes are you from? I'm near the Iron Range.-Pete '80 1100L
 
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