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Aviation gas


Rick Ward

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I call myself using the search tool for this topic but did not find or missed it. What is the conventional wisdom regarding the use of Avgas in (my case) 2000 R1100RT?

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Lead would be an issue in the 100/130 octane fuel. According to Shell, even the 'low lead' versions have significant lead. The available unleaded avgas is mostly interchangeable with automotive fuel

 

If the thought was that the 100/130 octane rating of general aviation fuels will produce more power ... the answer is no, it won't.

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I call myself using the search tool for this topic but did not find or missed it. What is the conventional wisdom regarding the use of Avgas in (my case) 2000 R1100RT?

 

Afternoon Rick

 

Common wisdom & common sense tells us not to do it.

 

Big reason is that unless using your bike on private property it is illegal as you aren't paying road tax on Av gasoline.

 

Next is the lead concern. I presume that your are looking to run 100LL? Don't let that LL fool you are there is still a LOT of lead in 100LL AV gas (I think around 2g per gallon).

 

So that leaves you with a problem-- you will flat out kill your catalytic converter & more than likely poison your o2 sensor.

 

You can remove the cat & disable your o2 sensor but that brings on another issue as 100LL is slower burning so will probably lose performance unless you add an aftermarket fuel controller & fool with your ign timing.

 

There is a new 102 UL coming to the AV market (that should be lead free) but again not road legal & no real gain in an old BMW boxer unless the fueling & engine are modified to use it.

 

 

Now if you are getting the AV gas for free then it might be worth making some changes to use it.

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100 octane LL is the MINIMUM Lead content. Our 100LL Avgas consistently comes in at 108 octane. Octane is measuring anti-knock but an increase in octane is representative here of higher Lead content in the fuel. If your bike has a catalytic converter, you cannot use Avgas. The tetra ethyl Lead will coat the ceramic Platinum/Paladium beads in the converter and make it useless in short order. I have used 100LL in my 1996 R1100 for Winter storage when I have a need to drain it from a wing fuel tank, it cannot be reused legally in the plane. That year bike does not have a catalytic converter either.

 

Avgas just does not deteriorate at all. Reason being, the hydrocarbon length is consistent. When some evaporates, what is left is identical to the gas before the evaporation so the viscosity does not alter. There is only 1 grade of Avgas available for the last 20 years and that is 100LL. 80 Octane unleaded Avgas is long gone.

 

There is unleaded racing fuel sold at some gas stations for classic cars and marine use...91-93 Octane and it is alcohol free. That would be great to use in motorcycles of my vintage that were designed to run on ethanol free fuels.... just not sold everywhere. I store about 1,100 gallons of it at any one time. If not available in the market, I can also go directly to the refinery and pull the product off the line before the ethanol is added. Ask around town, I am sure you will find someone who carries it as racing fuel if your town is large enough or has lakes nearby.

 

p.s.

Just reviewed my spec sheet on 2,900 gallons of Avgas 100LL from last week's delivery. 1.769 grams of Lead per gallon.

Edited by Rx_Mich
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100 octane LL is the MINIMUM Lead content. Our 100LL Avgas consistently comes in at 108 octane. Octane is measuring anti-knock but an increase in octane is representative here of higher Lead content in the fuel. If your bike has a catalytic converter, you cannot use Avgas. The tetra ethyl Lead will coat the ceramic Platinum/Paladium beads in the converter and make it useless in short order. I have used 100LL in my 1996 R1100 for Winter storage when I have a need to drain it from a wing fuel tank, it cannot be reused legally in the plane. That year bike does not have a catalytic converter either.

 

Avgas just does not deteriorate at all. Reason being, the hydrocarbon length is consistent. When some evaporates, what is left is identical to the gas before the evaporation so the viscosity does not alter. There is only 1 grade of Avgas available for the last 20 years and that is 100LL. 80 Octane unleaded Avgas is long gone.

 

There is unleaded racing fuel sold at some gas stations for classic cars and marine use...91-93 Octane and it is alcohol free. That would be great to use in motorcycles of my vintage that were designed to run on ethanol free fuels.... just not sold everywhere. I store about 1,100 gallons of it at any one time. If not available in the market, I can also go directly to the refinery and pull the product off the line before the ethanol is added. Ask around town, I am sure you will find someone who carries it as racing fuel if your town is large enough or has lakes nearby.

 

 

Evening Rx_Mich

 

All legally imported U.S. 1996 BMW 1100RT's came with a catalytic converter & o2 sensor.

 

If your 1996 1100RT doesn't have a cat. then someone removed it or it was a non U.S. grey market bike that was snuck into the country.

 

If your 96 1100RT has an o2 sensor then it definitely came with a cat converter. If it doesn't have an o2 sensor then it would have been equipped with an idle Co. trim pot on the L/H side. Again if no idle trim pot then it was not built without a cat.

 

Added: that 108 octane is more than likely the ROM (Research Octane Rating) number (that doesn't directly compare to U.S. pump gasoline rating). The R+M/2 rating (that is how U.S. automotive pump gasoline octane is rated) would probably be closer to 98-100.

Edited by dirtrider
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I pretty much always ran 100LL in my AIRHEAD as kept it in hangar and was available even when traveling. I use to keep about 30 Gallons in cans. All my airhead buddies came by for top off. For the reasons stated, I would not put in cat bike or bike supposed to have cat. I will tell you though the lead really helps with valve seat and valve seat wear.

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The question is why do you want to use Avgas in your 2000 R1100RT? Does the engine have a high compression requiring such high octane fuel? If not, using high octane gas can be as bad as using fuel with to low octane rating. I use a mix of StaBil360 and Chevron Techron fuel cleaner at almost every tank in my 2004 R1100S. I only use the required amount of each for my 4.5 gallon tank. Just a thought. I used the higher octane lead free race gas when I carbureted bikes to keep them from varnishing up.

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I ride a "stock" '96 R1100RT and I definitely have a cat converter and Co2 unit screwed into the front of the cat converter. I use 100% gasoline, either 90 or 93 octane, depending on which station I am nearest when I need to fill up.

Edited by Roger C
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Years ago (probably 45) when I was in trade school I had a teacher that explained that aviation fuel was made to operate UP THERE and was not a good choice for using in cars. This was back before the lead issue.

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If you want you can remove the alcohol from alcohol based MoGas by adding ~10% tap water (yes!). Shake for a few minutes, let settle, then drain and toss the water alcohol mix from the bottom of the gas can. I dump the water-alcohol mix anywhere as a protest, & use the remaining gasoline in my lawn mowers etc.

 

It probably doesn't have the octane of the original mix but for a lawn mower what the heck. It will save on carburetor overhauls.

Edited by nrp
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Tom in Vernon BC

Up here in BC, Standard and Shell still sell their premium gas without alcohol. I use as much Standard 94 as possible in the Beemer and find that it smells verrrry much like the 100ll in the Cessna Spamcan. Coincidence?

 

No! I wouldn't use 100ll in front of a catalytic converter. Race car? You betcha!

Edited by Tom in Vernon BC
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Hi.

The question as why use av fuel is valid. Higher octane doesn't equate to more power, it is more resistant to detonation. Av fuel is formulated to be less prone to vapor lock at the low pressure/ less dense air of high altitude .

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So Av Gas should not be used in bikes with Catalytic converters and O2 sensors. In our town we have a gas station that sells alcohol free 93 octane; should Stabil be added or any other additive or will the alcohol free product perform to manufacturer specs? I have no owners manual.

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Wish I could find 93 100% gas where I live then I would not use Stabil360. I have only used lead free high octane fuel many years ago when my Ducati sat for long periods, then no problems with the carburetors varnishing up. Ran like a champ every time. You should be okay with 93 octane lead free 100% gaoline.

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So Av Gas should not be used in bikes with Catalytic converters and O2 sensors. In our town we have a gas station that sells alcohol free 93 octane; should Stabil be added or any other additive or will the alcohol free product perform to manufacturer specs? I have no owners manual.

 

Afternoon Rick

 

Your BMW will run just fine on alcohol free 93 octane, just make darn sure that it is also lead free.

 

You don't need any additives in either standard E-10 90-92 octane or in that alcohol free 93 octane.

 

The only time that you might think about additives is if storing the bike for a while, even then if you fill it up with alcohol free 93 octane then it will store for a long time without issue.

 

 

 

 

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Thanks DR. Having used a lead substitute for /5 for so many years; I was not sure about the ethanol presence and its affect on throttle bodies.

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