I hear all this talk about how old gas is better in out 2 stroke 70's bikes..
What do you people think about using aviation gas which is 100 octane Low lead ?
my bike in this instance will be a 73 Suzuki gt380
Using AVGAS 100 LL
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CAFE380
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ConnerVT
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CAFE380
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Re: Using AVGAS 100 LL
thank you for that article !
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tz375
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Re: Using AVGAS 100 LL
AvGas has no place in a two stroke motor. It burns slowly and is just not suitable in so many ways.
Ethanol is no one's favorite additive, but it has a very high knock resistance and is used in some race gas. So it's good for street motors. The problem is that it draws in water which causes all manner of problems. Alcohol is also a solvent that can attack plastic/rubber parts.
Ethanol is no one's favorite additive, but it has a very high knock resistance and is used in some race gas. So it's good for street motors. The problem is that it draws in water which causes all manner of problems. Alcohol is also a solvent that can attack plastic/rubber parts.
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Zunspec4
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Re: Using AVGAS 100 LL
I would not go as far to say 100LL has no place in a 2-st enginetz375 wrote:AvGas has no place in a two stroke motor. It burns slowly and is just not suitable in so many ways.
Ethanol is no one's favorite additive, but it has a very high knock resistance and is used in some race gas. So it's good for street motors. The problem is that it draws in water which causes all manner of problems. Alcohol is also a solvent that can attack plastic/rubber parts.
. No useful place in a road intended engine may be. I run my T500 race engine on 100LL (or 50:50 pump/Avgas blend). The burn is slower than pump unleaded but no bad thing if you are running a higher compression ratio and want to avoid detonation. For the road it would be a waste of money unless you have been doing some significant tuning.Cheers Geoff
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tz375
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Re: Using AVGAS 100 LL
OK so I am working on the basis that racers are a little different in terms of requirements and options. We have run A TZ350 on 100 octane race gas and it was fine, but Avgas- no way Jose. 
Try something like VP U4.4 and you will never go back to fuels that were designed for something completely different. It isn't cheap but we don't use that much in the average weekend or season so it's not too bad.
Just like oils, people have their own preferences. I guess if all that was available was 100 AvGas I'd use it, but luckily we are spoiled for choices here.
I agree 100% that AvGas in a street bike is a waste of time and money. The one good thing about it is the lack of ethanol as a knock inhibitor. I think the correct answer though is to ride more and not have old gas left in the tank to absorb moisture.
If we are riding a lot I don't worry about the water, but if we are not doing a lot of miles I drain the street gas and put it in one the car/truck, and then refill with ethanol free from our race fuel supplier.
For low mileage use there has to be a better solution and I am sure that someone on here has thought of it.
Try something like VP U4.4 and you will never go back to fuels that were designed for something completely different. It isn't cheap but we don't use that much in the average weekend or season so it's not too bad.
Just like oils, people have their own preferences. I guess if all that was available was 100 AvGas I'd use it, but luckily we are spoiled for choices here.
I agree 100% that AvGas in a street bike is a waste of time and money. The one good thing about it is the lack of ethanol as a knock inhibitor. I think the correct answer though is to ride more and not have old gas left in the tank to absorb moisture.
If we are riding a lot I don't worry about the water, but if we are not doing a lot of miles I drain the street gas and put it in one the car/truck, and then refill with ethanol free from our race fuel supplier.
For low mileage use there has to be a better solution and I am sure that someone on here has thought of it.
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old racer
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Re: Using AVGAS 100 LL
There have been dozens maybe hundreds of racers here in the uk using avgas,
With improved performance without being detrimental to the engine.
With improved performance without being detrimental to the engine.
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tz375
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Re: Using AVGAS 100 LL
old racer wrote:There have been dozens maybe hundreds of racers here in the uk using avgas,
With improved performance without being detrimental to the engine.
I knew that someone would jump in.
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old racer
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A.Holley
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Re: Using AVGAS 100 LL
Back when I was racing, I was using Air Force spec avgas. (Mainly intended for DH Caribou radial engines)
It wasn't the usual 100 LL that all the other guys were using, actual octane was quoted as 115/120.
I was involved in fuel quality control testing , and instead of going into the waste drum for disposal after doing a test sample, it found its way into my fuel drum. All above board and approved by my OIC.
Andrew
It wasn't the usual 100 LL that all the other guys were using, actual octane was quoted as 115/120.
I was involved in fuel quality control testing , and instead of going into the waste drum for disposal after doing a test sample, it found its way into my fuel drum. All above board and approved by my OIC.
Andrew
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weber
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Re: Using AVGAS 100 LL
So here's some real life experience with 100LL in my 2001 KTM 250SX. I work in aviation so sumped 100LL is always free so I figured I'd give it a shot in my 250. The picture is after maybe 60-80 hours of 40:1 with Maxima 927 castor oil. This was strictly a woods bike so it saw it's share of lugging around the woods! Not one fouled plug all season!! Of course everyone said you can't run that in a dirtbike you'll foul plugs left and right with all those lead deposits, it doesn't run hot enough to burn it away, and so on and on....
Picture isn't that great but if you look at the head it was shiny. One of the cleaner topends I've seen for a woods bike. This was as removed no cleaning performed, picture was for all the doubters!!!
Side note 100LL and Maxima 927 is the BEST smelling mix in existence!!! Even my fast friends didn't mind riding behind my slow ass so they could get a smell of that sweetness.
Picture isn't that great but if you look at the head it was shiny. One of the cleaner topends I've seen for a woods bike. This was as removed no cleaning performed, picture was for all the doubters!!!
Side note 100LL and Maxima 927 is the BEST smelling mix in existence!!! Even my fast friends didn't mind riding behind my slow ass so they could get a smell of that sweetness.
