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Unleaded vs leaded fuels/ Oxygenated vs non

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So I've been running Sunoco supreme mixed 50/50 with 93 pump gas.The sunoco supreme is 112 octance, leaded and non oxygenated. I need more for this weekend and all the local shop had was sunoco 260 gt plus which is 104 octane, highly oxygenated and unleaded. I assume that I would need to change my jetting since its oxygenated. Is that true?

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running an oxygenated fuel (like VP u4.4 or MR12) in a bike mapped/jetting for pump gas, will result in the bike running VERY lean. Your adding lots of o2 to the mix. It DOES make more power, but ya need to map/jet the bike for the oxygenated fuel. Mapping/jetting for oxyg. fuels then running pump gas will result in it runing quite rich. Not as bad as lean, but not ideal. You can get a switch to go back n' forth between maps if your bike is FI. Almost any oxygenated fuel is gonna be leaded too.. (so dont run it in your street bike if it has a cat converter). You have found a place with o2 fuel AND unleaded.. One thing to remember, ya either need to use the o2 fuel ASAP or store in a sealed container. Leaving it in your vented gas tank will allow the o2 to evaporate out, and your left with some very expensive pump gas..

I'm not sure of any benefit to running a high octane fuel in a bike that does not have substancial compression to require high octane.. lower octane actually makes more power, asuming your bike won't "knock" or pre-ignite. Any race bike off the showroom floor is not going to require anything more than good pump gas. Oxygenated fuel WILL make more power, just note above..

that's about all i know about this, actual tuners/builders will be able to shed WAY more light on this. Check out/search the forum specific for this!

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You don't need octane any higher than what the engine was designed for, it is a waste of money and a hassle. What does your Owner's Manual say?

Fuel oxygenated with ethanol has three problems; 1. lean mixture. 2. difficulty mixing with oil and oil separation, 3. ethanol dissolves fiberglass resin in FB tanks.

Edited by chuck4788

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You don't need octane any higher than what the engine was designed for, it is a waste of money and a hassle. What does your Owner's Manual say?

Fuel oxygenated with ethanol has three problems; 1. lean mixture. 2. difficulty mixing with oil and oil separation, 3. ethanol dissolves fiberglass resin in FB tanks.

exactly, but oxygenated fuels DO make more power. We see 6-7hp differences on a yamaha r6 going from pump gas to MR12 (87 octane-oxygenated-leaded). BUT that shit is $28/gallon. And as i stated above you MUST map for it or your bike is gonna be lean. Oxygenated fuel is kind of like "turbo" principle. It's forcing oxygen into the combustion chamber, just in the fuel vs. outside air forced in through the intake via a pump.

Here is info on VP fuels. http://www.vpracingfuels.com/motocross.html give them a call and they can direct you to the ideal fuel for your purposes.

Edited by MELK-MAN

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Thanks for the response. I'm using it in an 07 RMZ 250 with a 13.9.1 wesico piston (stock is 13.5.1 I believe), pro circuit cams and pro circuit valves. I have the 260 gt plus fuel in the metal container in came in so it should last a while. So your saying I should jet leaner when using the oxygenated fuel?

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Thanks for the response. I'm using it in an 07 RMZ 250 with a 13.9.1 wesico piston (stock is 13.5.1 I believe), pro circuit cams and pro circuit valves. I have the 260 gt plus fuel in the metal container in came in so it should last a while. So your saying I should jet leaner when using the oxygenated fuel?

you need to richen the jetting due to the added oxygen in the fuel.

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So the guy at the local dealer says only to run leaded fuels like sunoco supreme and vp c12 in 2 strokes only. Not 4 strokes. Not sure why but that's what he said. Is this right? He recommended the sunoco gt 260 plus in 4 strokes.

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So the guy at the local dealer says only to run leaded fuels like sunoco supreme and vp c12 in 2 strokes only. Not 4 strokes. Not sure why but that's what he said. Is this right? He recommended the sunoco gt 260 plus in 4 strokes.

The guy at the shop is right... C 12 in 2 strokes and U4 in the 4 strokes but, unless your a top pro rider you don't need any of that over priced fuels unless you just got money to burn.... Good clean oct 93 is it.

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Im pretty sure higher octane fuels can eliminate pre-ignition also. (when the carbon and shit inside the engine is hot enough to ignite the fuel before it is sparked) This is why high-compression engines need race gas. higher compression= more power and inherintly more heat

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