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Discussion Starter #1
Have any of you run AVGAS in your TW? I run it in my mower, chainsaw, generator etc. I used to run it in my pickup before my volume source dried up. I still get a quart or two a week which is enough to get me to work and back. Any issues? So far I have only run it about 30-40%. What about any additives. Does anyone put anything in their fuel or oil?
Den
 

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Are you talking about Non Ethanol ? If so, they call it REC Fuel around here and it's about 80 cents more per gallon. I use it in my handheld stuff most of the time and in my sit-downers especially during storing off season. During riding season I run 87..
 

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I have been running the ethanol stuff for so long I wouldn't know which runs better now. I use Marvel Mystery Oil in it and did one carb overhaul over 40,000 miles. I Kreem tank lined my fuel tank which I believe kept more contaminants out also.
 

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I usually try to avoid running gas with ethanol in my TW, but a I have been force to use it a few times and didnt notice any difference. I would not ever store a carbed engine with the stuff in it. I bought a KLR last year that had been run and stored with the ethanol gas and it had ruined the fuel hose, melted the fuel filter mesh, melted the vacuum diaphragm in the petcock, and caused a strange green-yellow slime to form in the carb.
Since you never know when you may have to spontaneously store your TW or other small engine, I recommend only running ethanol free gas in them.
 

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And the KLR with the ruined fuel system is a 2011 with 6,000 miles that had been sitting "about a year or so", which seemed fairly accurate based on other evidence. So it was not an old bike that had sat forever.
 

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I know guys who ran AVgas in their street cars for drag racing only to have it eat the top of their pistons. Not right away, and usually in higher concentrations. You know, applying the "if a little is good then a whole lot is much better" axiom!

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I know guys who ran AVgas in their street cars for drag racing only to have it eat the top of their pistons. Not right away, and usually in higher concentrations. You know, applying the "if a little is good then a whole lot is much better" axiom!

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That's probably because they advanced their timing too far.

AvGas is 100 octane, so people like push the limits of the spark advance in their hot rods... sometimes too much.

If AvGas eroded aluminum pistons, we wouldn't use it in airplanes.... ;)
 

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As far as I know av gas is leaded (cjpilot can speak to the current facts). If it is still leaded theses days don't use it in anything with a catalytic converter or oxygen sensor. It's high octane which is good if you need it, lead is good as well fir many reasons (except eating). In fact it's a great fuel if it fits your application. I'm not sure if it will affect injected engines that have no emission controls (race bikes), my guess is it won't. CJ?
 

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CJ7Pilot is correct. There is nothing particularly special about av gas. I assume it is still ethanol free. It probably has stricter blending regulations. But at its heart it is still just gas. Drag racers tend to push the limits with compression pressures and spark advance. That results in detonation, AKA 'ping' or 'knock'. Serious drag racers may not even run a cooling system. The resultant heat added to the high pressures and detonation and piston tops are often damaged.
 

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Yes, 100 low lead Avgas is Ethanol free. However, it still has tetra-ethyl lead in it that will destroy a catalytic converter in a few seconds. We don't have those in our TW's, so the issue becomes how well our engines will run on 100 octane. With Avgas running around $5.50 a gallon and the fact that high octane actually has a slight negative effect on mileage and heat flow in our 1970 engines, it's ridiculous to consider running Avgas in our TW's just because it does not have Ethanol.
 

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Yes, 100 low lead Avgas is Ethanol free. However, it still has tetra-ethyl lead in it that will destroy a catalytic converter in a few seconds. We don't have those in our TW's, so the issue becomes how well our engines will run on 100 octane. With Avgas running around $5.50 a gallon and the fact that high octane actually has a slight negative effect on mileage and heat flow in our 1970 engines, it's ridiculous to consider running Avgas in our TW's just because it does not have Ethanol.
I agree with most of this.

Oddly, in California, the price of self-serve AvGas is pretty similar to premium ethanol-laden auto fuel... that's because we have exorbitant road taxes built in to the price of auto fuel, that do not apply to aviation fuel.

That said, when I'm only buying a couple of gallons at a time, the price per gallon isn't a huge consideration anyway.

I run mostly auto fuel (with ethanol), but I run the carb dry after every ride, and I haven't had any carb problems, even after long periods of non-use.

I do run AvGas periodically as well, and I can tell you there's no difference in the way the engines run... just in the way they smell.

My opinion: running AvGas in your TW200 won't really help anything, but it won't really hurt anything either.

If you like it, then run it... it's not ridiculous.

Check your local laws though, it may be illegal to run it on the street. :dontknow:
 

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Discussion Starter #15
I agree with most of this.

Oddly, in California, the price of self-serve AvGas is pretty similar to premium ethanol-laden auto fuel... that's because we have exorbitant road taxes built in to the price of auto fuel, that do not apply to aviation fuel.

That said, when I'm only buying a couple of gallons at a time, the price per gallon isn't a huge consideration anyway.

I run mostly auto fuel (with ethanol), but I run the carb dry after every ride, and I haven't had any carb problems, even after long periods of non-use.

I do run AvGas periodically as well, and I can tell you there's no difference in the way the engines run... just in the way they smell.

My opinion: running AvGas in your TW200 won't really help anything, but it won't really hurt anything either.

If you like it, then run it... it's not ridiculous.

Check your local laws though, it may be illegal to run it on the street. :dontknow:


I work on airplanes for a living (second career). When I sump the bowzer and some of the planes I can dispose of the small amount of fuel how I want. I don't run avgas because it is ethanol free but because it is simply free. It won't hurt the pistons, it won't hurt the carb. I noticed in the operators manual that it states that using leaded fuel can cause "severe damage" to the engine. I find that laughable but maybe it can build up on the valve stems or something? Airplane engines don't typically have valve seals like ground-based vehicles do. I am just wondering if anyone has a long term experience with running leaded fuel.
I am not aware of any place to buy ethanol free fuel in Arizona. I have heard rumors of it but never seen it. I saw in in the midwest last year but never at the pumps in AZ.

I run avgas in my small engines because they don't like alcohol. It is WAY cheaper than the premix stuff you buy at the saw shop ($10 gal). Lead really builds up some places in aircraft engines. When I change a crankshaft plug I dig a couple of tablespoons of gooey tetra-ethyl lead out of the end of it nearly every time. When the pilots idle the planes with the mixture full rich the lead builds up on the bottom plugs badly. We pull the plugs every 100 hours and clean the lead deposits out of them. The gap is quite small because they are magneto fired and doesn't take much to foul them. Just want to make sure I don't end up having to do the same thing to the TW.

And yes, AVGAS is a LOT different than car gas. It has a much tighter control on vapor pressure which is generally a lot less than mogas (car fuel). It has no additives other than lead so it isn't stinky. It doesn't seem to go bad after sitting for a couple of years. It is expensive I will grant you that.
 

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"I am just wondering if anyone has a long term experience with running leaded fuel."

Yep leaded fuel was standard till about 1975 when you could buy either one at separate pumps and converter equipped vehicles had the smaller hole in the filler neck (as they still do today) to prevent use of the standard larger nozzle at the "leaded" pumps.
 

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Lets clarify the various fuels so we are all on the same page. Aviation gas is usually only available at airports. It is ethanol free and leaded and usually has a 100 or over octane rating. Ethanol free gas at regular fuel stations does not have ethanol or lead in it and is usually has between a 90-95 octane rating. All of the ethanol based fuels are either 10-15% of corn alcohol and come with octane ratings of between 85-94. Fuel at a Marina is NOT AV gas but usually is ethanol and lead free. The lead in AV gas is there as a lubricant mostly for the valve guides. The absence of ethanol in AV gas is to keep the fuels from going through what is called phase separation while sitting and to prevent the transfer of moisture from the atmosphere getting into the fuel. Airplanes don't fly great when the engine quits because the carbs sucked up some water or got gunked up. Marine engines don't run great with water in their fuels either but they don't fall out of the sky. TWs run fine on 87 octane ethanol gas or ethanol free 91 octane. How you use your TW is the key. If you fill the tank with ethanol gas and use it then you are perfectly fine. If you fill the tank with ethanol gas and the tank lasts a few months then not so fine. You decide based on how your TW goes through the fuel in the tank. Fill it and ride and fill it again and just regular 10% ethanol fuel at 87 octane is fine. If the bike will sit for a long period I would get the ethanol out and non ethanol in if it is available. If non ethanol is not available in your area then treat the tank with a fuel stabilizer but don't expect it to last for months at a time. The stabilizers do help but are not a cure all. Any moisture that gets inside your metal tank causes rust to form and that thin rust film flakes off and ends up in your float valve and the jets as clogs. Use a in line fuel filter. I would avoid real AV gas in a TW but highly prefer non ethanol gas in it at all times and it is available here in my area of NY. Search for a fuel supplier who sells K-1 Kerosene and OFF Road diesel fuel for farm tractors and you will probably find non ethanol gas. My local place caters to farmers and landscape outfits that use numerous small engines subject to sporadic usage year around so it is called Combined Energy Services (CES) and they have all the various fuels except AV gas. Home heating oil, Propane, Kerosene, Off Road diesel and On Road diesel and No ethanol and ethanol gas in 4 different octanes.

GaryL
 

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Discussion Starter #18
Actually, this is not the main reason "The lead in AV gas is there as a lubricant mostly for the valve guides."

The main reason there is lead in AVGAS is for the anti-knock properties. The lower compression aircraft engines run just fine on pump gas. The lower vapor pressure of AVGAS is also a benefit when flying at high altitudes. By far and away the most common avgas is 100LL (low lead) but it still has up to .56g/liter of lead. The high performance avgas like you will find in Reno is about 1.3g/liter. Old school "ethyl" or premium contained about the same as current 100LL avgas.

Continental still claims that leaded fuel is required in their engines to properly lubricate the valve train but there are a number of STCs which allow for the use of unleaded auto gas to be used in them. When early cars switched to unless it was hard on the valve seats but it wasn't because the lead was lubricating anything it was that it was moderating the flame front. Retarding the ignition generally fixed problem until harden valve seats could be installed. I've never seem a problem with the valve train from running unleaded gas. Having an engine with pre-ignition will destroy it in short order. I am just wondering why Yamaha states that leaded gas will cause severe damage to the engine.
 

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a engine can only run ad good as it can run. Race fuel or Av gas will not make more power. It will allow you to make more power by not detonating. It actually burns slower than pump gas. The good thing iso it doesn't have ethanol to crud up the carb if the bike sits. Would I use Ave gas or race fuel? Sure. I dump the weekends left over race fuel from my mx bike. Mostly because I hate getting fuel and I like the way it smells
 

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Tucker Gott (famous youtuber re Powered paramotors) ran avgas in one of his 2 stroke paramotor engines and while it ran fine it created a massive build of of what looked like a white calcium colored substance all over the plug and he ended up taking the top end apart and scraping off all the lead fouling as he referred to it. Seemed strange to me I know we ran lead for many years in our cars so I have no idea why there would be any build up
 
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