I hear their is a problem with 91 gas

[Jeff Williams]

Hi all,
i was having a talk with one of our comrades and he said that the 91 octane we get in Cali is bad for the bikes. Better to use 89 octane even though less power.
Can anyone enlighten me/us on this ?

thanks
jeff

[wswartzwel]

News two me... our you sure it was because of the octane, and not some west coast smog additive??

[ckcarr]

I say dyslexia...

[Guest24]

Jeff, the 89 octane here is made at the pump by mixing 91 octane with 87 octane. During the fuel shortage in Western NC the stations wouldn't sell premium because they wanted to be able to sell mid-grade. ore 87 octane doesn't have ethanol. Up to 10% ethanol can be added to premium.

[bill pierce]

Originally Posted by Nail24

Up to 10% ethanol can be added to premium.

Here in the tree huger state all grades have 10% ethanol. I haven't really seen any major negative effects though.

[Jeff Williams]

Originally Posted by wswartzwel

News two me... our you sure it was because of the octane, and not some west coast smog additive??

It sounded like the additives caused problems with either the life of the engine or the intake system.

[Steve Carlton]

30,000 mile rebuild looming large?

[markjenn]

Sounds like another of the silly gas rumors that are always going around. Nothing wrong with 91 and should be used if the engine needs it to prevent pinging (and our boxer twins generally do). And bikes won't make less power on 89 (or 87 for that matter), unless they're pinging badly.

- Mark

[wood-d]

Better to use 89 octane even though less power.
Can anyone enlighten me/us on this ?

Octane is the resistance to pre-combustion and has nothing to do with power. Cars that gain more power from higher octane are doing so by exploiting ignition timing. Our bimmers have no such capability.

[sdaddy]

Originally Posted by wood-d

Octane is the resistance to pre-combustion and has nothing to do with power. Cars that gain more power from higher octane are doing so by exploiting ignition timing. Our bimmers have no such capability.

... or gain more power by having high compression which some of our bimmers have (12.5:1 for R12S!)

[Guest24]

When we had the premium shortage in WNC I decided to put a bottle of Octane booster in the thankbag just in case. Gas today goes flat faster than the old days when we had lead added and the ethanol component. Burning lower octane gas and getting lower BTU's from the burn will prolly extend and not shorten than looming 30,000 mile refit. So who is running their HP2S lik BP146 and N8 on a daily basis. I don't believe even the good Doc Curve has a place to do it the same as the track.

[tm1100s]

Up to 10% ethanol should barely be noticeable much less cause a problem.

On the 91 octane, the general theory that's been passed around is because it's more expensive less of it is being sold and it sits in the tank longer than usual before being pumped into your tank. The longer it sits the more it degrades the less benefit you get from 'high octane'. Gas degrades fast, could lose octane points in only 2 to 3 weeks, obviously the longer it sit the worse it is. 87 and 89 get pumped faster and doesn't stay in the tanks as long so there could be benefit in using 89 over 91. Been using 89 instead of 91 in my M3 (now gone) and haven't noticed any difference.

[Rapid Dog]

...race fuel only!

[roger albert]

What Markjenn said. All kinds of silly folk wisdom on gas out there, most of it bunk.

> Burning lower octane gas and getting lower BTU's from the burn will prolly extend and not shorten than looming 30,000 mile refit.

Lower octane actually has ever so slightly more energy, not less. But not enough to make a difference one way or the other.

> The longer it sits the more it degrades the less benefit you get from 'high octane'. Gas degrades fast, could lose octane points in only 2 to 3 weeks, obviously the longer it sit the worse it is.

Takes a good deal longer than that (8 weeks in even really hot weather and if sitting stagnant and vented) but it is conceptually right. Still, you'd have to be at a truly podunk station for the turnover rate on high octane to be so slow that it's an issue.

[anotheroldrider]

Wouldn't our bikes meet that description by retarding ignition if they sense detonation (maybe from the other side of the coin, but nonetheless...)?

[geothepencil]

Originally Posted by roger albert

Still, you'd have to be at a truly podunk station for the turnover rate on high octane to be so slow that it's an issue.

We gassed up at that station in Eastern CO this summer. The pump and hose were shaking all over the place as the pump ran. The guy said he was pretty sure there was enough of that preeeemium to fill up the bikes.

geo

[geothepencil]

I'm sometimes more worried about the age of the gas. Does old gas contribute to carbon or other buildup in the engines ?

geo

[bradzdotcom]

Originally Posted by sdaddy

... or gain more power by having high compression which some of our bimmers have (12.5:1 for R12S!)

bimmers?
those are bmw cars.

beemers.
those are real bmws (motorcycles).

it's in the owner's manual, between the page with the illustrations of the secret handshake and the page with the decoder ring instructions.

if you're missing those pages, steve carlton will sell them to you.
i'm not supposed to mention this, but since i'm a friend of steve, i paid only $5 per page and so far it's been worth every penny.

maybe he'll give you the same deal, this being holiday season and all.

[bradzdotcom]

Originally Posted by geothepencil

We gassed up at that station in Eastern CO this summer. The pump and hose were shaking all over the place as the pump ran. The guy said he was pretty sure there was enough of that preeeemium to fill up the bikes.

geo

there used to be a "we know you're desperate so we're gonna gouge you" gas station out in the desert towards las vegas.
it was in one of those spots where you're commited to climbing the hill and just realized that you're sucking fuel and should have topped off back in baker.

over the years i've had to stop twice and both times you had to wake up the guy and have him turn on the electricity so he could charge you a ridiculous amount of money per gallon.
both times it was only two or three bikes, so he really wasn't happy about having his nap interrupted.

at a gas station in vermont, i asked the attendant if it was true that vermont folks are pretty tight lipped.
guy looks me right in the eye, says "nope" and walks away.

as far as octane, if it'll run on the cheapest stuff without pinging, have at it.
if you're going out to play ricky racer, treat the two of you to the good stuff. can't hurt.
but i'm with many others on this one: as cheap as you can go without getting pinged.
poor, poor octane. so mis-understood.
i feel particularly sorry for the 87 octane button.
you can just feel that 87 button screaming "pick me! pick me! really, i can do this!".

[RBMann]

Originally Posted by bill pierce

Here in the tree huger state all grades have 10% ethanol. I haven't really seen any major negative effects though.

I see a 10-15% drop in mileage.

RB