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Octane??

  • Thread starter Thread starter opiewontaylor
  • Start date Start date
O

opiewontaylor

Guest
Just wondering what octane of fuel you guys run? I've always ran premium (93) in all my bikes, but the recent gas price increases have the 87 stuff looking better to me :)
 
Use straight 87.
Always buy it at a reputable station.
I have been using "regular unleaded" for many years in both the GS and GT.
The few times I have used "hi test", I never saw that much of a diff. Both in cars, bikes and boats.
 
My 750 runs fine on 87 octane as do most GS models. The 1150 is spec'd for 89 and pings terribly on 87. Hot days, it pings on 89 also, so 93 in the 1150.
As long as you dont get a preignition ping, 87 is fine.

Earl
 
My 850 may have carbon buildup so it pings without premiun Its only 91 octain in Cal NO 93 available
 
1. Octane does not increase HP.
2. Use what is specified for your machine.
3. If your bike pings on 87 octane, you can usually retard the timing slightly (with subsequent loss in performance) and eliminate pre-detonation.
4. Use of high octane fuels may cause poor idling when cold and unexplained stalling.
5. Using premium in a low to mid compression engine is a waste of money!
 
basaraj said:
1. Octane does not increase HP.
2. Use what is specified for your machine.
3. If your bike pings on 87 octane, you can usually retard the timing slightly (with subsequent loss in performance) and eliminate pre-detonation.
4. Use of high octane fuels may cause poor idling when cold and unexplained stalling.
5. Using premium in a low to mid compression engine is a waste of money!
Click to expand...
Interesting. But what is considered high compression? 9 to 1? 10 to 1? More?
 
There are self-delusional knuckleheads on this forum who'll swear up and down that they get better gas mileage by using premium. Total nonsense. If your stock GS doesn't run well on regular 87 octane, there's something wrong with it. You should then treat the cause of the problem; burning premium fuel will merely treat the symptoms.

Been running regular gas on my GS bikes since 1986 -- over 200,000 miles. Brand doesn't matter either.

Nick
 
I've tried them all, but see no advantage with anything over what the manual says the engine is designed for
 
opiewontaylor said:
basaraj said:
1. Octane does not increase HP.
2. Use what is specified for your machine.
3. If your bike pings on 87 octane, you can usually retard the timing slightly (with subsequent loss in performance) and eliminate pre-detonation.
4. Use of high octane fuels may cause poor idling when cold and unexplained stalling.
5. Using premium in a low to mid compression engine is a waste of money!
Click to expand...
Interesting. But what is considered high compression? 9 to 1? 10 to 1? More?
Click to expand...

Rule of thumb is anything greater than 10:1 will require higher octane.
I've run many an engine at 9.5 with 87 octane.
 
there are other factors that come into play other than compression ratio in determining fuel octane, spark plug heat range, fuel mixture, additives, temperature, shrouding, carbon, hot points, piston speed, etc. Many high compression engines can run on low ocatne fuel favorably. High octane fuel resists the tendancy to explode during the ignition/power cycle. Ideally you want a slow buring propogating flame front to expand and push the piston down at the desired piston location (timing). Detonation, uncontrolled burning "hammers" the piston with an explosion and can literaly punch a hole in the piston. For my money and piece of mind, i go with manufactures suggestion. They should know all the variables better than we do.
 
87 here, and if pinging is a problem, I have found that a good carb sync can clear it right up.
 
Hmmm...

The only time my GS850G has ever pinged was when two exhaust valves self-destructed a few years back, which was part of a horribly expensive but educational chain of events that started with air leaks in two $1.79 O-rings. It was running like crap anyway, and the hot valves were probably lighting off the mixture prematurely.

You know, I've been automatically reaching for the premium pump on motorcycles for a long time without really considering why. Now that the GS850 is running perfectly, I'll try a few tanks of the cheap stuff.

After all, I think Nick has provided The Final Word on this topic through his extensive experience with his own stable (flock? harem?) of GSs.
 
The key word to Nick's statement is 'Stock'. If your bike isn't stock, you'll have to draw your own conclusions, especially if you've changed the compression ratio. When I changed the pipe, and switched to pods, and a jet kit on my GS700, it preferred 89, instead of 87.
 
On a stock GS the specified fuel is the one to use. If there are problems such as pinging, then there is most likely a tuning problem of carbon buildup causing it. It can also depend on what altitude you are riding at and what the bike was tuned for. Remember that when new the bikes were tuned to get past emissions and did tend to have lean problems, that in most cases would have been tuned out by now.

In my bike (78 GS1000 with modified engine) I have to run a higher octane. There can be a difference between fuels, but this is more a fuel quality issue rather than octance.
 
Ok, I've just got to ask:
In northern Europe it's almost impossible to get fuel with octane lower than 95, premium is 98. Are we taking about different octane scales?
 
In my stock engines I can run anything but definitely choose the better quality fuel as saaz mentioned for many self-delusional knuckle-headed reasons. I get better fuel economy, the engine runs cooler and there is a noticeable performance boost as well. I don't experience any pinging or knocking with any grade. Cars have been an exception to that.

My GS1000 is not stock and is setup to use 90+ octane fuel. Anything lower
than that and I can get predetination issues as well as build up.
My preference for the higher grade is cleaner fuel and better
performance. Here in my area the jump from 89 to 94 octane
is 6 cents a gallon. I usually fill up 3 to 3.5 gallons at a time so
I am not going to sweat it over 18 to 21 cents more a tank.

To each his own. High octane for me.

Side note, I run 87 or 89 in my new car :) Just to be a rebel! :twisted:
 
blo said:
Ok, I've just got to ask:
In northern Europe it's almost impossible to get fuel with octane lower than 95, premium is 98. Are we taking about different octane scales?
Click to expand...

I am thinking different scales?
 
Good point about stock vs. modified -- you have to be willing to experiment and adapt, especially with older bikes. To some degree they have all been modified, if only by age, wear, and carbon buildup.

If your motorcycle runs better (cooler, faster, whatever) on premium, then run premium.

Even though it's made up of components from at least three different bikes, my GS850G is reasonably stock (stock airbox, exhaust, and jetting) so I'm going to try a few tanks of cheap stuff and see what happens. It runs perfectly now, so any decline in power or running quality should be easy to detect.
 
About Euro vs. North American octane, a little Googling turned up this:

Octane ratings are misleading....
in Europe they go by RON (Research Octane Number)

Here, it's AKI (Anti-Knock Index...[RON+MON]/2)

RON: Octane based on no load
MON: (Motor Octane Number)....Octane Rating based on a loaded engine.

but....in general....RON= AKI+4 (approximately)


Who knows if it's true, but it makes sense.
 
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