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Discussion Starter · #1 ·
I've been running 93 octane premium gas in both of my sleds religiously, knowing the manufacturer recommends at least 91. My concerns are....I don't really know how much ethanol is in the premium 93. I know from experience that ethanol wreaks all kinds of bad mojo with smaller engines,and would like to refrain from its use...which brings me to the question at hand. There are a few gas stations here that sell an ethanol free 90 octane "Recreational gas" (or "Rec gas"), just for your toys. Would this ethanol free gas be too low of an octane rating to safely burn an entire day on the trail?
 

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91 will be fine for a stock engine with factory squish, stock exhaust system and timing, and no lean conditions.

To give an idea how factory squish will measure, it is roughly 60+ thou using solder 90 thou in diameter, or roughly 53+ thou using solder 63 thou in diameter, or 47+ thou when measuring piston to deck height.

On a factory engine with new parts this would be a 1.1 mm base gasket. With older parts having heads and decks shaved it is difficult to rely only on base gasket, but if we were to consider new parts the safest base gasket to be pump safe would be the 1.3 mm 3 hole.
 

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In English Please...........
91 will be fine if your engine is setup and working perfectly as it should.

Edit:

90/91, 93/94, tomayto/tomahto

Ethanol? Who cares???

Most important is fresh fuel and highest turnover fuel.
 

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The question was 90 octane non ethanol vs 93 with ethonol. I'd run the 90 because when alot of these sleds were made ethanol was not in pump gas and as the OP noted can cause some serious issues.
 

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Discussion Starter · #8 ·
Good point Drewster, I didn't think about it that way. And the more I roll this around in my head, I really don't believe one octane point is going to be catastrophic...
 
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