Running 100LL aviation gas in older sleds

[liquifireguy]

I was wondering what gas everyone is running in their older Deeres. Last winter, which was my first season back into the old sleds, I just ran 89 octane unleaded, but I was wondering what kind of damage I am doing to the engines. The manuals specifically say not to run unleaded. I am also wanting to run straight gasoline instead of ethanol. I talked to my fuel supplier about if they carried any straight gas. All he can get is the ethanol blend. It looks to me that, by running aviation gas, which is 100 octane straight leaded gasoline, I would be achieving both of my goals. Will the extra octane hurt anything? I don't put a lot of miles on the old sleds, so the extra cost wouldn't be a problem, especially if it is better for the sled. Thanks, Jeff

[JoeRainville]

Hello liquifireguy,

Despite what the manuals say, you do not need leaded fuel in these old two strokes. "Lead" was used as both a cheap octane booster and it also helped to lubricate the exhaust valves of 4 stroke cars.

Ethanol blends have either own issues, including swelling fuel lines and other plastics. But, the main problem with ethanol is that is leans down your air/fuel ratio a bit. I have never lost a motor to it directly, due to a lean condition, but it did melt the gas cap seal on my 2002 Cat Z-440. The melted seal dripped into the tank and then coated the fuel line and inside of the carb, causing the inlet needles to stick.

The closest I've run to AV-gas it 110 Octane leaded race fuel in my old SnoCross sleds. I am not sure of the effect (if any) on the air/fuel ratio of AV gas vs pump fuel, but as long as you verify the plug readings are not lean, there should not be a problem. But, it is overkill on a stock motor.

Extra octane does not hurt anything, as all it provides is detonation resistance. You may want to check the BTU/lbs of fuel to compare to pump gas so make sure your not going lean on fuel.

I hope this helps,
-Joe

[That Girl Racing]

Joe is 100% correct about the unleaded fuel in older sleds. I will take it one step further. The 100 octane will cost you horsepower over 91.

[liquifireguy]

Have you guys been able to find straight gas anywhere? The fuel line deterioration and rubber part swelling has been my biggest problem with new gas.

[nick80lf]

Some marina's have fuel without ethanol.

[gnfreak]

http://pure-gas.org/index.jsp

[400brian]

My fuel supplier here on the farm tells me there is no ethanol in the regular gas he delivers, which I was surprised to hear. All the pumps in town say it may contain up to 10% I believe.

The premium here is often alcohol free, and many of the premium pumps where we ride up in northern WI will have a notice that it is ethanol free. Being that I run Premium in the old mid-mounts, I guess that works out OK for me.

[JDT]

Same in SD. Premium has no ethanol.

All the other nozzles have at least 10%.

[liquifireguy]

I have looked at the pure gas site and the closest I can find is about 1 hour south. Indiana seems to be big into ethanol for all grades. As a corn farmer, I am all for ethanol, but it just doesn't work well in snowmobiles, small engines, or old tractors. I guess I am best off just using pump gas with Sea Foam. Thanks, Jeff

[JDT]

You will also have starting problems with 100 octane when it gets really cold.

[That Girl Racing]

Guys you are really worrying about nothing. Your sleds will run just fine on it. Even if you do find "pure" gasoline, it will not be around much longer.