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  1. #1
    canadaxp's Avatar
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    Leaded vs unleaded question

    I have to bump up my octane for my fuel. The best I can get is 91 at the pump here, and who knows if its really 91.

    So, our lubricant guy we use for work said I should just use 87, and add race fuel to it. I believe he said 11:1 is the mix to bring 87 up to 93 (93.1). Also, he said this will actually work out cheaper for me than buying premium at the pump. Especially since my price on the race fuel is next to nothing.

    Only question, do I use leaded or unleaded.....he has both. I know it will only be 9% of the fuel, but would one be better?

    REG


  2. #2
    Chrisrokc's Avatar
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    Use unleaded. The leaded fuels can cause issues in the fuel system and can kill sensors in the exhaust.

  3. #3
    Here is crazy's chart and I can't see a good reason to run leaded?
    http://www.greenhulk.net/forums/atta...4&d=1179048830

  4. #4
    Moderator OsideBill's Avatar
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    What compression are you running? I run right at 150psi with cheap a$$ California 91oct and have no issues at all.

  5. #5
    canadaxp's Avatar
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    Just under 150, but I have to check it with a different tester. 39.8 cc domes, at 3000 feet.

  6. #6
    Moderator OsideBill's Avatar
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    Quote Originally Posted by canadaxp View Post
    Just under 150, but I have to check it with a different tester. 39.8 cc domes, at 3000 feet.
    Altitude = Less air which means richer mixture correct?

  7. #7
    (Use unleaded. The leaded fuels can cause issues in the fuel system and can kill sensors in the exhaust.)

    On a gp1300r there are no sensors that leaded fuel can damage, and no issues it can cause, unless you still have the cat on your ski.
    The sensors are simply temperature sensors, and not 0-2 sensors measuring oxygen.
    Leaded fuel in an automotive application can alter 0-2 sensor readings and damage/clog cat converters.
    Lead is actually a good additive to the fuel system because of its lubrication qualities, but it also is an emissions nightmare.
    The inception of unleaded fuel began in the early 70s, and was soley for emissions purposes.
    Without the added lead lubrication, auto engines immediately started wearing out valve guides, especially exhaust, and also burning and pitting the valve faces and seats from the very dry burn of unleaded. This lead to the creation of stellite valve seats, which are used on literally every engine on the planet now, which are harder than hammered hell and stand up to the unleaded exhaust.
    Leaded does create more deposits on spark plugs in long term applications, but would mean nothing on a 2 stroke engine.
    Ever used a graphite style aerosol lubricant for anything? Throttle, clutch and speedo cables are good candidates for graphite lubricants.. That is what lead does, and how it feels.
    My choice? Always leaded when ever possible.. Unless you are an avid tree hugger..

  8. #8

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    Ross, tetra-ethyl lead was intially introduced to boost octane levels. When it was phased out due to environmental/health concerns in the 70's valve seat erosion became a problem. I agree with most of your post except for the fact that lead "lubricated" valve guides. My understanding is that lead did not actually "lube" anything it just "cushioned" the valve as it slammed into the seat.

    Tetra-ethyl lead and graphite (pencil lead) are two different things.

  9. #9
    canadaxp's Avatar
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    I'm going to go with 87 and a little bit of leaded fuel. I know all the drag car guys here use leaded only. I'll ask why tomorrow. I'll bet its for all the reasons mentioned here.

    Thanks

  10. #10
    canadaxp's Avatar
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    I ended up getting the 104 unleaded oxygenated fuel. I guess we'll see what it does.

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