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Discussion in 'Trials' started by Jonny360, Jan 19, 2018.
See you next month brother. Really looking forward to competing on that 304 ACM!
Yup, LL AVGAS has way less tetraethyly lead than auto gas did.
What we often miss in discussion volatility. I have to get the specific pamphlet out the file file cabinet to quote the source but suffice it to say AVGAS vaporizes a little less readily than Auto Gas at ground level so it can vaporize normaly at altitude.
My big brother uses 50/50 mix of plain old unleaded pump gas and 110LL AVGAS, makes a nice replacement for Sunoco 260 in his drag cars and muscle cars.
I have been using and recommending avgas for a while (for 2 strokes) but thought I would check closer into VP fuels.
There are a lot of choices of just the VP brand - more than 20. Some use lead for octane boosting. Some use MTBE - those are the ones claimed to be "oxygenated". Some are claimed to be non lead and non oxygenated. Those likely use xylene or toulene as octane boosters.
Everyone is concerned about health issues related to lead. But going to MTBE is no solution. We know it to be cancer causing. It's oxygenating property is a small plus and makes it popular though. So what about the other major octane boosters - xylene and toluene ? They are cheaper than MTBE, but cause nervous system, kidney and liver damage.
The amounts used in formulas I have seen range from 10 to 30% for MTBE, xylene, and toulene. 10% is the practical limit for alcohol. Alcohol has the least health risks - but we know it is nasty to our fuel system.
Best solution - get a Montesa. Made for alcohol fuels. Run it a lot. No jetting issues ever and no deciding which alcohol free fuel to get.
I have never bought anything but pump gas. So that gives me three excuses, age, weight and crappy gas.
I've run pump fuel in every trials bike I have ever owned and all ran fine. I am not a top level competitor and haven't owned nearly as many bikes as many here, so maybe that's why. Even my Evo 300 4T ran great on 91 pump fuel.
I'm hoping that this is the case. I've run regular pump gas mixed with Stabil or Starbrite in all my engines, which supposedly binds the ethanol and makes it so you can let it sit in a carburetor for up to a year. I've done this in all my 4-stroke mowers and my 2-stroke trimmers and chainsaw and they always start on the first or second pull. There is an airport nearby which I think sells leaded AvGas but I'd honestly rather just run regular pump gas with an additive. It'd be a complete turnoff for getting started in this sport to have to drive all over the place for VP fuel or AvGas. Sheesh!
Plenty of posts here about pump gas being just fine in Trials bikes, so that's no reason to get "turned off" to this sport.
I have run Avgas since 1981. Easy to come by in the day job.
What I have learned from running Avgas, pump gas and race gas.
Regarding two strokes, I have never experienced a performance problem running Avgas. When I tested Avgas in the YZ426f, the engine would sag as it was accellerated. Switching to race gas or pump gas eliminated this. The reason pretty much came down to the slow burning Tolulene that is used in Avgas. My current bikes, the 2003 KTM 250 two stroke, my 73 MAR and now my Scorpa SY250 all burn Avgas without issues.
Avgas does contain lead. Avgas also contains Tolulene. Many race fuels contain lead, some may contain Tolulene, while others contain MTBE. Others already stated facts tnat MTBE is a known cancer causing item. MTBE was quickly brought in to replace lead in gasoline for automotive use, but is proving more harmful in many ways.
Avgas is no walk in the park either. Yes lead is bad but wait there’s more. The Tolulene is derived from Benzene, and Benzene is also a known cancer causing item.
The two reasons not to run pump gas. Generally pump gas is inconsistent and the ethanol is hard on rubber parts in tne fuel system or engine.
The reason to run Avgas or Race gas is consistency, no damage from ethanol, and if needed, a higher octane.
Other benefits of Avgas or race gas is in many cases, the bikes are much easier to jet cleanly. Additionally, the plugs will show true color of the burn, where most pump gas setups tend to leave a black plug regardless of jetting.
Avgas also stores very well and even better when premixed.
I read a post where a person was using StaBil as a fuel additive to eliminate concerns about ethanol. I have experience with additives also. Not in the motorcycle fuel but rather lawn equipment. Previously I used StaBil, I have also used StarTron or whatever they call it. Probably even tried Sea Foam. A few years ago, I learned about Yamalube Fuel Med RX. Keeping this short, so far, the Fuel Med RX has been the only product that prevented corrosion in the fuel bowls of the lawn equipment. This was on four stroke engines. All my two stroke lawn equipment has been run for years on AvGas and Klotz r 50.
FWIW, a while back, a similar fuel discussion happened on another website. Possibly KTMTalk or Thumpertalk, but most likely the old Dirtrider.net site. There were at the time some well known engine builders making posts. Ultimately, they even admitted that consistency of the fuel was very important and kind of agreed pump gas lacked consistency. We all agreed race gas was best if available and cost was no object. With that said, and the majority of the posts were from guys in the USA, we learned that in other countries, their 5 gallon drums of rave gas was actually AvGas. This was primarily due to the fact race gas was not imported in quantities to be cost effective, but AvGas was.
Shop that does head mods for 2T motors, mainly KTM’s. Customer was unhappy with the performance of his KTM 300, after his head was modified. After a bit of back and forth, shop asked for a fuel sample. High test 10% ethanol pump gas, was what he was running . The sample tested 26% ethanol.
FWIW, I know this is a trials section, but KTMs with excessive squish clearance or improper squish band ratio are almost impossible to jet on pump gas. Cut the head correctly and most times they run well. Run even better on Avgas or Racegas.
I just recently detuned my KTM slightly. Removed the head I cut with pretty agressive squish dimensions and went back to something less agressive, but still adequate.
26%, not sure how they tested the fuel. Maybe it was possible the fuel was holding water within the ethanol and the unlucky sole got the first slug or yuck out of the pump.
26%, not sure how they tested the fuel. Maybe it was possible the fuel was holding water within the ethanol and the unlucky sole got the first slug or yuck out of the pump.[/QUOTE]
26% alcohol alone is way too much. surprised it ran at all.
You can determine the amount of alcohol in gas easily. Add a lot of water to the gas (a measured amount). Shake well.
The alcohol will combine with the water and settle to the bottom. Drain off and measure what settled. Measure that volume and subtract the amount of water added earlier. The difference is the alcohol volume you just removed. You are left with alcohol free gasoline - at a very low octane.
Hey not my idea. Blame it on Dave's old man, Bud . Took me as long as it did you to try it, so that was a long time ago. We need to 'get the lead out!'
Did a somewhat beater GasGas rescue this weekend after a call asking for help on a stripped center case/water pump screw.
During a later test ride I ended up also having to welded the aluminum gas tank ('05 Raga 300). Glad the rider didn't go up in flames riding my ranch, as the wind was ripping fire danger was exceptional.
I and the owner were wondering why the mixture was changing. The bike would run great, then get over rich and stall prone. He kept stopping to look the bike over, puzzled. Then he looked under the tank and found a steady dribble of fuel off the back of the tank. The evaporants were getting inhaled into the air box, depending on wind direction accounting for transient over richness.
Cause? One of the subframe screw head ends had beat into the side of the tank and also the rear weld seam had a crack.
After welding the tank, I needed to get the last bit of water out. Used a hot air gun but still there were little water drops. Impatient to finish, I sloshed a little E10 in the tank and dumped it out. I explained how the ethanol in E10 would bind up with the remaining traces of water for a sort of magnetic flush.
I commented in passing that I buy E10 and mix it with racing fuel. He replied with some conviction, "I buy only pure gasoline." I sighed and said, "There is no pure gasoline." (Well, maybe Coleman stove fuel?) I started in on terms like MTBE, then just shut up and kept on task.
OK, The info I got in the past was from google search on av gas, and came from an Aviation website. Forget which one, should have posted my info site like you did. Think I did my lead content numbers wrong, on my last post, prob should be x1.0 to 2.0 , sorry. Either way , am not trying to mislead any one. Can we all agree that we all want to find out the best fuel to use? , as that is my goal.
Looks like plenty of info and links to go over, thanks, But need some time later to go over it, as am doing a tricky evap , head gasket, and valve job , ala Subaru. Do have an open mind, and maybe will be burning AV gas in future, info is good!
MTBE is banned in NY. Little hamlet just to east of me had all their wells contaminated by underground gas tank leaking from service station in the 4 corners. Took over 25 years to clean up to some acceptable level and town brought in municipal water about 5 years ago. There are 3 houses still deemed uninhabitable, but they don't want to disturb the soil tearing them down.
Fun experiment: Try Coleman stove fuel to experience 'white gas' (presumed pure gasoline).
We won't know the particular blend of hydrocarbon chain lengths of white gas. If pinging under moderate loads results, that will imply the predominance of chains are on the shorter side, or so I assume. Maybe pure gasoline isn't good for anything but very low compression engines of the early 20th century.
I remember as a kid, AMOCO gas stations sold lead free "White Gas", that we used in our Coleman lanterns and stove.
The way I learned about MTBE was when I got water quality reports as chairman of the water commission in my town.
There were often trace amounts found from one particular well - never enough to trigger any action. But I had to become informed. EPA says while MTBE is harmful, it is only a precursor to lots of other chemicals related to gasoline that are often found later. Thankfully, we never found any more in our system while becoming very watchful about liquid leaks in the area.
I did not realize so many of you run pump gas in modern 2-strokes. For vintage bikes, alcohol avoidance is very important since so many components cannot survive it. Many types of plastic tanks are affected. My Montesa and Beta both have aluminum tanks, so there is one issue eliminated. Montesa actually recommends "commercial premium unleaded" fuel. What are the manufacturers of modern 2 strokes recommending ?
Being a frugal yankee, I want to run the cheapest thing that works. For lots of purposes that is avgas. But now you guys have given me the idea to try pump gas in my 2013 Beta 200. I realize long term storage with E10 is a bad idea, but frequent use should take care of that. Will the the fuel system be ok with alcohol ?
Not sure on a Beta 200 but my wife's 08 Gas Gas 125 doesn't have any issues with it.
FYI: Most is the time I pick up non ethanol premium as I have a local supply within a reasonable distance but in a rush I have used E10 plenty of times over the last 6 years. Never an issue.
I want to mention...... "we" bought back a few GG bikes over the years that were "impossible to get to run right"
Almost every single time it was related to fuel and/or jetting. ( a few instances were porosity related)
In one case, the fuel he was using was 110 octane for supercharged four stroke racing engines, another time it was nitro-methane mixed with pump gas...
When a bike doesn't run right, before messing with the jetting, first make sure it is not the fuel. 100LL at 80:1 after cleaning the carburetor and fuel tank out and verifying the jetting, fuel valve, and floats are in good condition. After all of this is found to be relevant to what is known as good (also for use in your altitude). Then proceed to test the bike and determine if jetting changes are needed.
People chasing jetting changes when the problem is nasty gas or float/needle valve related is actually quite common.
And tank vent nipple reversed or clogged or fuel vent hose pinched causing fuel starvation issues, and and and.....
Air filter completely saturated with heavy oil or clogged with dirt....