You dont need 100 octane,prob wont run better. Use 90- 94 octane no Ethanol gas if possible.
Stihl ms200t carburetor
- Thread starter briguy26
- Start date
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100 octane race fuel will only pollute more, carbon up your combustion chamber, and cost you more money. It simply isn’t volatile enough to burn cleanly in your saw.
Run the lowest octane you can in any engine. If 87 is too volatile and causes detonation (pinging) then try 89 but your saw will almost certainly run best on 87. Unless you have increased compression or advanced the timing you’ll be good to go.
What does octane have to do with volatility of gasoline?
Nathan Graff
ArboristSite Operative
Octane is like fire retardant in the gas. The higher the number, the more fire retardant. That's why engines with longer strokes like higher octane fuel. It has a longer burn while the piston is traveling. Short stroke engines like lower octane numbers. It's more complicated than that, but it's a good overview.
I generally run 91 in my saws as it's the only fuel here available without ethanol in it.
Like Nathan said, octane is added to fuel to make it less volatile. Aviation gas is high octane to run cooler but it has a few other differences since an airplane flies at steady throttle. Racing fuel is designed for constant throttle input but also to run cool and prevent pre-ignition in a high compression engine running lots of timing advance. The fuel doesn’t give the engine more power. It simply allows the engine to run at it’s potential without pinging and the high compression burns the fuel cleanly even though it has less energy.
Good answers.
