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Question about ethanol gas in two stroke...

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#1
So, with pretty much all of our gas in Alabama now having ethanol in it, anybody have any problems? From what I've read online, as long as it's not over 10% ethanol there shouldnt be any problems, but still not preferred if it can be avoided, I might can find some that don't have ethanol but it'll be hard. Any jetting differences with ethanol gas? thanks!!
 

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#2
I've used it without problems. Given a choice, I prefer all gasoline. Do a search and read away.
 

DougTx

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#3
It is not the burning that is the problem

Ethanol is hygroscopic (if that is the word I am tryign to think of) meaning it absorbs water. If you let it sit you will have water in your fuel is most peoples beef I believe.

FWIW
 
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#4
yeah i've done some reading up on it for my boat. sta-bil has some new marine formula for ethanol gas. I hear in the boat community it's good stuff.
 
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#5
pretty much all gas around me is 10% and has been for awhile. never had any problems.

There are alot of differences though between ethanol and gas.
burns hotter, asborbs water, doesn't lubricate the same as gas. There alot of info and misinfo out there if you want do some reading up.
 
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#6
ericz103 said:
There alot of info and misinfo out there ....

You mean like this gem? :rotfl:

ericz103 said:
There are alot of differences though between ethanol and gas.
burns hotter
You should have paid more attention in chemistry class. ;)


Back to the original poster's question.

Ethanol based pump fuel is best avoided if possible, but if you have to use it. Consider the following :

- draining the fuel from the tank and the float bowl is a very good idea to avoid water accumulation.
- store the fuel in the smallest sealed containter you can and keep it cool and dry
- test a small sample of your fuel with the oil you use to make sure they mix properly, and stay mixed over time. It's likely they will, but better safe then sorry.
- your fuel mileage will drop compared to standard gas
- your jetting will likely go to the lean side with ethanol based fuel
- it will be harder to jet for good throttle response because ethanol has a fixed boiling point around 173 degrees f and a very high latent heat of vaporization, along with a requiring a different A/F ratio then the rest of the fuel. In short it acts very different then pure gasoline and screws up the fuels distillation curve which can cause jetting issues.
- the octane distribution of ethanol based fuels will be very different than pure gasoline, so it's best to tune on the safe side till you get used to running with ethanol. Two-stroke riders who switch to ethanol based fuels without other changes very often run into knock and detonation issues they never had before.
-older two-strokes can have issues with the solvent properties of ethanol attacking the crank seals and destroying them. This was a real problem in the early 80s when ethanol started first showing up. The current crop of two-strokes don't have these issues.

If you jet really sharp you'll probably see an immediate change in the way the bike runs and will most likely be on the lean side.

If you jet sort of close it may not matter. If you keep in mind it will be a little lean you'll likely be safe.

If anyone is interested in more of the specifics about alcohol as a fuel follow this link to the DRN KnowledgeBase : http://www.dirtrider.net/forums3/showthread.php?t=115212
 
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#7
And its real important to be at least getting premium for the mx bikes at the pumps, at least! The older enduro, lower compression engines may get away with regular or mid grade. But, there are some mx engines that will not even run on premium! They can start to detonate. Most all mx engines, stock, run fine on premium, from a busy station, from a pump that already had premium ran through the pump hose, and I have never had issues from Amoco or Shell, etc.
 
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#8
You mean like this gem?

yep, just going off the top of my head, thought that is what I had heard somewhere down the road. Guess thats why I encouraged him to read up on his own.

Chemistry was to long ago for me, but your article did enlighten me.
 
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#9
Rich Rohrich seems to have it covered. I found a report from South America that claimed because Ethanol absorbs water and also allows the water to mix with petrol a reaction occurs that seriously degrades the octane rating (more moisture lower octane). It will be interesting down here with our V8 supercar series going to an Ethanol blend fuel in there 600HP 5 litre engines, hope they keep an eye on there fuel supply.
 
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#10
I've read up a good bit on it for my 2 stroke 200 hp boat engine, just wanted some opinions on the dirtbikes. I deliver gasoline for a living so i'm pretty familiar with the characteristics of ethanol etc. I know of 2 people who have burned up their chainsaws in the last year since we started delivering 10% eth blend here in Alabama...thanks guys!
 
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#11
Rich Rohrich said:
- the octane distribution of ethanol based fuels will be very different than pure gasoline, so it's best to tune on the safe side till you get used to running with ethanol. Two-stroke riders who switch to ethanol based fuels without other changes very often run into knock and detonation issues they never had before.
I am a little confused by this.

I had always thought that alcohol based fuels had a much higher octane rating than gasoline, which is why it is used for the really top end racing. I suppose that if the refinery was dropping the gasoline portion of the octane because the alcohol was going to bring it back up then you could get into some interesting problems.

What I am 99% sure of is that alcohol burns slower and requires more fuel per a given amount of air to produce the optimum mixture. The slower burn rate translates into ignition timing and the mix rate translates into jetting. So, like Rich said, if you were perfect before, you will be running lean and a little retarded with an alcohol mix.

Rod
 
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#12
ethanol itself is very high octane, cant remember exactly, around 112 I THINK.......when we blend premium, it is 55% prem, 35% reg and 10% eth,
Reg is 90% reg and 10% eth.
I don't know about elsewhere, but here, most of the stores we deliver, the plus is just plain ol reg with 10% eth so people are gettin ripped by paying more for plus at most stores here.

Reg with 10% eth is actually plus(89 octane) so we're kinda getting a bargain in that respect, if you wanna look at it like that........eth gas sux, no mileage, evaporates fast, attracts water like crazy, the eth can seperate from the gas and settle to the bottom of the tank, then you get a big dose of eth which is bad on most engines unless they're e85 engines.

We cant even drop eth gas if there is over 1/2 inch water in the tank. before we started eth we could drop gas with up to 4 inches of water in a tank, because the pickup is usually about 10-14 inches up from the bottom of the tank. the water will mix with eth gas where it will hardly mix with straight gas, and if it does it seperates very quickly and sinks back to the bottom. it'll stay mixed with eth gas for a long time before settling.
 

jaguar

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#13
hmm, that's not my experience. I mix water with the E25 gas here in Paraguay and the water and ethanol combine and drop immediately to the bottom. Then I pour out all that's above the bottom mix to be used.
 
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#14
The problem with that approach using American fuels is the octane raising components are not evenly distributed throughout the distillation curve of the fuel. So if you use water to pull the ethanol out of the fuel (which you can never do completely) you will be left with an incredibly low octane fuel with a gaping hole in the middle of the distillation curve due to ethanol being a single boiling point component. It would be very difficult to get a proper running fuel curve if you just removed the ethanol.

With the ethanol in the fuel it's tendency to attract water will complicate things if it's left in an unsealed container in high humidity areas.
 
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