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Fuel type

518 Views 6 Replies 4 Participants Last post by  jljones
90 rec fuel always. More MPG. Better for the valves.
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The octane rating doesn't refer to gas mileage. It's the rate of burn of the fuel across the cylinder. General aviation engines and Harley engines have cylinders that are around 4 inches in diameter. In order to get full burn and optimum use of expansion, higher octanes were used. Otherwise unburned gas would exit the exhaust and finish burning with a loud backfire. Since aviation engines run at higher RPM's than Harley engines, aviation engines use two spark plugs to ignite the fuel from two directions and complete the burn. It also helps airplanes in that they have two ignition systems and thus a "back up" in case of ignition system failure. Harley engines have a slower Put Put Put that burns the gas just fine.

The Rebels small two inch diameter cylinders don't need high octane fuel! Everything burns before it leaves the cylinder, even at max RPM's! I use 85 octane and get plenty of miles per gallon, maybe 75-85+, depending on the season here in Ohio with all the gasoline additives. Spending more money on high octane gasoline gets you nothing other than less money in your pocket. But if it makes you feel good...
Unless I misunderstand what you posted, you're wrong about octane burn rate. Higher octane fuel burns slower than lower octane.
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