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Has anybody heard the one about
- Thread starter tlg1100
- Start date
Viton and Buna-N (Nitrile) are two common materials used to make O-rings. Viton O-rings can tolerate heat and chemicals better than Buna-N, and are more expensive. Robert Barr chose Buna-N O-rings for his ever popular carb kits, and Viton O-rings for the intake boot O-rings. I've had some people tell me that Viton O-rings should be used for the carb O-rings as well but I can't substantiate that claim.
There are a lot of GSR members with Buna-N O-rings from cycleorings.com installed, and working, in their carbs. That should be proof enough I think, although it's hard to say what will happen in 10 years.
There are a lot of GSR members with Buna-N O-rings from cycleorings.com installed, and working, in their carbs. That should be proof enough I think, although it's hard to say what will happen in 10 years.
B
bmac
Guest
Parts
Parts
Hey, some of us may have to add a 3rd wheel in 10 yrs. bmac
Parts
Hey, some of us may have to add a 3rd wheel in 10 yrs. bmac
With our luck, we mught just have to buy another set from Robert in 10 years, instead of the 30 that the originals lasted.
Darn, another $15 wasted.
.
10 years is not bad but would you pay an extra $5 for an O-ring kit that will last 30 years like the originals?
BTW, I'm not suggesting these are actual lifespan values, or that the OE O-rings are viton. Just asking the question...
First, there are about a million varieties of alcohol. Also, Viton, like Scotch tape or Velcro, is a trade name that evolved into a generically used term for Viton and materials with similar properties. There are also sub-categories of Viton (A, B, G, etc.). It's a common but erroneous conclusion that since Viton is tougher in some extremes, it must be a better material in all applications.
Buna-n (Nitrile) is perfectly compatible with ethanol / ethyl alcohol, and just about every variety of alcohol I could search up.
It's possible to find links to sites that claim otherwise, but these are generally from anecdotal sources. You won't find any such claims from any professional / industrial source or end-user sites (or from manufacturers who hire chemical engineers).
In other words, there's no need to sweat it, because other people have done the worrying for you.
Now, for really aggressive carb-cleaning fuel additives, well, you're on your own. If you're nervous about adding some Miracle Product, write to its manufacturer and inquire about Buna compatibility.
http://standard-gasket.com/tech_specs/chem_res/chemres_buna_e.htm
Buna-n (Nitrile) is perfectly compatible with ethanol / ethyl alcohol, and just about every variety of alcohol I could search up.
It's possible to find links to sites that claim otherwise, but these are generally from anecdotal sources. You won't find any such claims from any professional / industrial source or end-user sites (or from manufacturers who hire chemical engineers).
In other words, there's no need to sweat it, because other people have done the worrying for you.
Now, for really aggressive carb-cleaning fuel additives, well, you're on your own. If you're nervous about adding some Miracle Product, write to its manufacturer and inquire about Buna compatibility.
http://standard-gasket.com/tech_specs/chem_res/chemres_buna_e.htm
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Steve
GS Whisperer
Most likely not. Not that it's such a bad price, it's just that the next owner should have fun with the carbs, too.
I'm not sure if I will have any of my bikes for the next 10 years. If they need o-rings before then, and Robert Barr is still in 'business', we'll do another transaction or two. :dancing:
.
Z
Zooks
Guest
Hopefully if Robert ever decides to stop selling o-rings he'll pass on the tech info to someone so they can keep it going.
T
tejasmud
Guest
What attacks the o-rings is not so much alcohol, but the hydrocarbons in the selected fuel one uses. The durometer (hardness) of the material the o-ring is made of is also part of the equation as well as in reference to chemical resistance. This is part of the "(A, B, G, ect.)" as mentioned in the compound formulation of the o-ring.
Nitrile has some resistance to fuels where the hydrocarbon level is low. In todays World, nitrile with a duro hardness of 90 will not have much of a problem with pump gas.
First thing that happens with nitrile when exposed to a chemical high in hydrocarbons is it will swell (mushy), then when exposed to air it will get hard as a rock from the hydrocarbons evaporating off. It should last a while if continually wet in pump gas.
Carburetor cleaner is very high in hydrocarbons. It is like a paint thinner in regards to nitrile. This is due to the plasticisors that make nitrile soft and hydrocarbons have the same chenmical structure. If you put a nitrile o-ring in say Chem-Dip, it will swell and get mushy. The oil that is on the top of the Chem-Dip is basically to keep the hydrocarbons from evaporating.
Viton, a trade name for FKM material, has better high temperature properties, and resists hydrocarbons much better. Thus preference for the intake o-rings, given they are sealing against the head. Some of the formulations of FKM are better than others in terms of compression set at temperature, but in this application on bikes it's not much of an issue.
Now, if one was powering their machine with Anhydrous NH3, Viton would not be the material of choice. Similar result as with the Chem Dip and nitrile.
Nitrile has some resistance to fuels where the hydrocarbon level is low. In todays World, nitrile with a duro hardness of 90 will not have much of a problem with pump gas.
First thing that happens with nitrile when exposed to a chemical high in hydrocarbons is it will swell (mushy), then when exposed to air it will get hard as a rock from the hydrocarbons evaporating off. It should last a while if continually wet in pump gas.
Carburetor cleaner is very high in hydrocarbons. It is like a paint thinner in regards to nitrile. This is due to the plasticisors that make nitrile soft and hydrocarbons have the same chenmical structure. If you put a nitrile o-ring in say Chem-Dip, it will swell and get mushy. The oil that is on the top of the Chem-Dip is basically to keep the hydrocarbons from evaporating.
Viton, a trade name for FKM material, has better high temperature properties, and resists hydrocarbons much better. Thus preference for the intake o-rings, given they are sealing against the head. Some of the formulations of FKM are better than others in terms of compression set at temperature, but in this application on bikes it's not much of an issue.
Now, if one was powering their machine with Anhydrous NH3, Viton would not be the material of choice. Similar result as with the Chem Dip and nitrile.
I don't remember how long Mr. Barr has been selling his kits, but I've had one of his o-ring kits in my carbs for several years -- I believe I was one of the first to buy and install a kit, or at least I got in on the first year or two.
I persist in buying the cheapest gas possible (most of which contains alcohol), and I've had absolutely no problems in something like 50,000 to 60,000 miles.
I've also installed his kits in several other bikes, again, no problems.
Conclusion: Find something else to worry about other than the brand name of the material used to make your carb o-rings. And stop listening to goobers at gas stations.
Viton is needed to withstand the heat of the cylinder head, so that's what is used on intake boots. It is not needed in the carbs, so Buna-n is more appropriate.
"Viton" does sound cool, though.
I persist in buying the cheapest gas possible (most of which contains alcohol), and I've had absolutely no problems in something like 50,000 to 60,000 miles.
I've also installed his kits in several other bikes, again, no problems.
Conclusion: Find something else to worry about other than the brand name of the material used to make your carb o-rings. And stop listening to goobers at gas stations.
Viton is needed to withstand the heat of the cylinder head, so that's what is used on intake boots. It is not needed in the carbs, so Buna-n is more appropriate.
"Viton" does sound cool, though.
K
Kaiser Sosei
Guest
I'm curious if there is anywhere in the States that the gas doesn't have alchohol in it. It seems everywhere I have been all across the country, it all has alchohol. Even in rural areas.
N
nisom512
Guest
I don't remember how long Mr. Barr has been selling his kits, but I've had one of his o-ring kits in my carbs for several years -- I believe I was one of the first to buy and install a kit, or at least I got in on the first year or two.
I persist in buying the cheapest gas possible (most of which contains alcohol), and I've had absolutely no problems in something like 50,000 to 60,000 miles.
I've also installed his kits in several other bikes, again, no problems.
Conclusion: Find something else to worry about other than the brand name of the material used to make your carb o-rings. And stop listening to goobers at gas stations.
Viton is needed to withstand the heat of the cylinder head, so that's what is used on intake boots. It is not needed in the carbs, so Buna-n is more appropriate.
"Viton" does sound cool, though.
done and done well I think this discussion is over.
Now on to the new topic.
Can you believe that Obama wore shorts at that golf coarse!!!!!.....jk
well one thing you can take from that is you now know a cool name for your next kid!!!!
Yup, gas in the US pretty much all has alcohol in it nowadays. Sometimes it's disclosed on the pumps, but most of the time it isn't, at least around here in Indiana (this varies according to state and local law). Many states (Illinois, for example) actually require gasoline to be 10% alcohol.
It may be possible to find alcohol-free pump gas in a few areas, but I haven't seen any for a while.
With all that said, I'll let you in on a secret: it doesn't really matter.
Alcohol in gas gets the blame for an insane variety of engine and carburetion ills. When an engine burps, "bad gas" is the default substitute for the more honest "I dunno". The urban legends surrounding gasoline with alcohol are downright ludicrous.
On a properly functioning GS with anything less than full drag race tuning and modifications, 87 octane gas with or without alcohol works fine and won't dissolve or melt anything that wasn't already dissolving or melting.
8
82Shafty
Guest
While you cats are on the discussion of cleaner air LOL, did any of you read about the bringing alcohol levels up to 20 percent in our fuels?
I remember when the first go around came about, lawnmowers, weedeaters and a bunch of other small engines the rubber in them swelled up like a pregnant woman's ankles. I stayed very busy at the lawnmower shop as a high-school tech.
http://www.agri-pulse.com/uploaded/20090417H.pdf
Ok, I found the real reason, there is some mandate that says so much ethanol has to be circulated to remain viable and now because we have cut back our fuel consumption, the ethanol police want to raise the level to 15% to stay viable. It doesn't have squat to do with clean air like I read in the Chicago Curruptbune. Granted it would help, but I knew there had to be a better reason.
"You do have to consume more Ethanol than gasoline due to it's lower btu rating, but ethanol typically has a more efficient burn.
You are right that the "miles per gallon" you can travel on ethanol is less than the "miles per gallon" for gasoline. But this does not mean that ethanol is less efficient. It simply means that one gallon of ethanol actually contains fewer Btus of energy. A gallon of ethanol contains 76,000 Btus of energy. A gallon of gasoline contains around 110,000 Btus of energy. Your car's engine can use the energy from ethanol just as efficiently as it can use the energy contained in gasoline. Thus, your mileage will drop in direct proportion to the energy contained in the fuel - which amounts to a reduction of about 30% in the miles delivered per gallon of fuel ethanol versus gasoline."
http://www.nrel.gov/biomass/faqs/topic.cfm/topic_id=17
I remember when the first go around came about, lawnmowers, weedeaters and a bunch of other small engines the rubber in them swelled up like a pregnant woman's ankles. I stayed very busy at the lawnmower shop as a high-school tech.
http://www.agri-pulse.com/uploaded/20090417H.pdf
Ok, I found the real reason, there is some mandate that says so much ethanol has to be circulated to remain viable and now because we have cut back our fuel consumption, the ethanol police want to raise the level to 15% to stay viable. It doesn't have squat to do with clean air like I read in the Chicago Curruptbune. Granted it would help, but I knew there had to be a better reason.
"You do have to consume more Ethanol than gasoline due to it's lower btu rating, but ethanol typically has a more efficient burn.
You are right that the "miles per gallon" you can travel on ethanol is less than the "miles per gallon" for gasoline. But this does not mean that ethanol is less efficient. It simply means that one gallon of ethanol actually contains fewer Btus of energy. A gallon of ethanol contains 76,000 Btus of energy. A gallon of gasoline contains around 110,000 Btus of energy. Your car's engine can use the energy from ethanol just as efficiently as it can use the energy contained in gasoline. Thus, your mileage will drop in direct proportion to the energy contained in the fuel - which amounts to a reduction of about 30% in the miles delivered per gallon of fuel ethanol versus gasoline."
http://www.nrel.gov/biomass/faqs/topic.cfm/topic_id=17
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O
Odinist
Guest
You can find ethanol free gas all over the place in Oklahoma. They passed a law here last year that pumps that have alcohol in them have to be clearly labeled, which is awesome. You tend to pay about 5 cents more a gallon for alcohol free fuel, but it's worth it (better gas mileage).
This guy told me I needed Viton o-rings in my carbs:
But this guy said that Buna ones were fine:
And this guy (he's undercover in this photo) said he'd arrest me if I started a thread about synthetic vs. dino oils:
Nissan had a massive recall a number of years back to replace rubber fuel system parts that were deteriorating due to evolutions in fuel formulations; the rubber did not deteriorate with the old gas formulas but did with newer formulas. This problem was not related to alcohol, but rather to other compounds in the fuel (can’t remember the exact details).
My opinion is that it wouldn’t hurt to hedge the bet and use Viton (fluroelastomer) rubber o-rings inside the carbs. I did a search on the web about “fuel injector O rings” and turned up a number of examples where modern cars are using this type of material. I also uncovered reference to using Buna-N O-rings as well but these references were on older cars.
As Griffin alluded, this issue is sort of like synthetic oil; there is technical merit to using synthetic/viton, but it’s not a do or die sort of issue.
My opinion is that it wouldn’t hurt to hedge the bet and use Viton (fluroelastomer) rubber o-rings inside the carbs. I did a search on the web about “fuel injector O rings” and turned up a number of examples where modern cars are using this type of material. I also uncovered reference to using Buna-N O-rings as well but these references were on older cars.
As Griffin alluded, this issue is sort of like synthetic oil; there is technical merit to using synthetic/viton, but it’s not a do or die sort of issue.