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lets talk octane!

Discussion in 'XJ Technical Chat' started by jamesc2008, Jul 25, 2009.

  1. jamesc2008

    jamesc2008 Member

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    I have decided my neck of the woods here in iowa sucks in terms of gasoline options. I am having a difficult time finding gas above 87 octane and if i do it has ethanol in it. My baby doesn't seem to be such a fan of the low octane regular unleaded. Of course I am doing my darnedest to get higher octane unleaded, but barring that find should i look into some octane booster? or maybe the high octane race fuel that a gas station in town sells? Should i date kayla or haley? You folks seem to have answers to everything so i threw that last one in just 'cuz :wink:
     
  2. xj650ss

    xj650ss Member

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    Becarefull with octane boost's as they are meant in most cases to treat a tank of fuel for a car not a bike, A full bottle may be a little over kill.... Date Haley on odd days and kayla on even unless they know each other in which case, date Haley for a month and if it's not going well call Kayla and tell her you made a huge mistake but you see now that she's the one you should be with!!! :wink:
    Shaun
     
  3. markie

    markie Member

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    Hi, Don't want to upset you, but regular unleaded petrol (Gasoline) in the UK is 95 RON!

    Maybe I could export it to the U.S. .........?
     
  4. kontiki

    kontiki Member

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    I have found a station near to me that sells pure gasoline, with ~zero~ ethanol in it. That is all I use in my bikes and my truck.

    Ethanol has ruined more carburetors, tanks and fuel systems than most people realize. If it were not subsidized by the government it would never have happened.
     
  5. CJ06XLT

    CJ06XLT Member

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    You should read up on what the octane rating means and see if it applies to your situation. The only way a higher than recommended octane will (should?) make any difference is if your bike is currently experiencing detonation (pinging / pre-ignition). Octane is added to increase a fuels resistance to the above mentioned phenomenon. Higher compression than stock, or an altered timing can warrant needing a higher rated gas.

    What do you mean by this? Can you give a few more details?
     
  6. helmet

    helmet Member

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    On 2 wheels... just lost my hat.
    most octane boosters at the store are meant for ~20 gallons of fuel. you should look at finding an even mix to throw into your tank. see if that helps.
    if all else fails, get a 50 gallon tank in your truck and drive to the nearest 91 octane town and fill up
    oh, haley, btw.
     
  7. RickCoMatic

    RickCoMatic Well-Known Member

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    If I run straight Regular at the point where I'm running this 750 Maxim ... I get a little bit of Knock.
    Since the Pistons and Combustion Chamber is Aluminum; I quit using the Regular and use High Test.

    The Bike can't possibly run any better than she is right now.
    I know I might be wasting 12-Cents a Gallon.
    I'm cool with that.
    High-test is the way I roll.
    It's one of the things I do that don't make sense to anybody else but me.
     
  8. helmet

    helmet Member

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    On 2 wheels... just lost my hat.
    can you explain high test?
     
  9. Captainkirk

    Captainkirk Member

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    I, like Rick, routinely run Premium unleaded and mix it with 100 Octane LL Avgas when I have it (which is fairly often, given my profession). Premium is the way to go. You might find a good supplier and stock up by filling a 55 gallon drum of the stuff with a hand pump; it would likely last a year or two, although I'd be leery of storing auto pump gas more than 90 days, even with Sta-Bil in it. Figure out a 90 day supply quantity and buy in bulk. Just my .02......
     
  10. railtrolley

    railtrolley Member

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    I'm surprised with the 87 octane fuel. That seems very low. Regular unleaded petrol here, is 91 octane, and there are premium 94 and 98 octane fuels available, for about 10- 15 cents more per litre. My XJ likes the 91 octane. A few places have 10% ethanol, but it hasn't made many big inroads yet. We also call a particular fuel called "gas", but that is what it literally is. I run my work ute on it - which has a converted engine. It is Liquid Petroleum Gas, or Propane, which is supposed to be about 100 octane. LPG or Propane for vehicles is about 45c per litre. Unleaded is $1.20 a litre.

    How low would the compression on an engine have to be to run 87 octane?
     
  11. Wyldman

    Wyldman Member

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    Premium usually is 93 octane around here. I've ALWAYS run Premium in whatever bike I'm riding. My Harley DEMANDED it.
     
  12. MiCarl

    MiCarl Active Member

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    In North America we use the Pump Octane Number. In the rest of the world you use the Research Octane Number. PON is roughly RON - 5. In otherwords what you call 91 would be 86 here.


    XJs call for 91 RON. That's why we can run 87 octane in North America.
     
  13. kjohnson

    kjohnson Member

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    what all you that aren't from US, Canada and a few other countries have to remember is that we use AKI octane rating on our pumps, not RON.
    Our octane rating is based off off (RON + MON)/2 and is therefore ~4 points lower than RON rating.

    more to be found at http://en.wikipedia.org/wiki/Octane_rating
     
  14. xjmannen

    xjmannen New Member

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    we have 95 98 and shell v-power i think it is 99octaine.
    wonder if the ignition is low in the bike so it can run 87octaine that som countrys have ?
     
  15. jamesc2008

    jamesc2008 Member

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    Ahh i get it... I recal reading some archived review of 750 Secas from when they were first coming out and the author mentioned the bike should run 91 octane, but looking back the article may not have been from north america. Regardless, the bike will run with 87 in it, but i would like to bump it up if possible. Sadly, NOBODY in the des moines area has higher than 87 unleaded. Ethanol is being shoved down our collective throat.

    Related story, i called a gas station in my town to ask what the octane on their regular unleaded was and the kid on the phone didn't know. (Expected this.) I told him to go look at the pumps as there should be a yellow sticker with an octane number on it and he said they don't have it. At which point i asked, "So you don't sell gas with octane ratings?" His reply, "Nope."
    :roll:
     
  16. PGDBUD

    PGDBUD Member

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    Methanol in high consintrations can damage the seals in these carburetors.

    Octane Boost can be added in 5% or less concentrations.

    I have use North American's 108 Octane Boost in the past which is 12 oz. per 22 gal. It contains Methanol and T-Butyl Alcohol.

    That would equate to 0.55 oz. Boost / per gal of regular gas.
    They recommend adding it to the tank first and then adding fuel the throughly mix the Boost into the fuel.
     
  17. kontiki

    kontiki Member

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    alcohol is bad gentlemen.... avoid it if possible.
     
  18. MiCarl

    MiCarl Active Member

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    There is a move afoot to REQUIRE 15% ethanol in all non-aviation gasoline in the states. I don't think you're going to have an option much longer.
     
  19. jamesc2008

    jamesc2008 Member

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    oh man..
     
  20. Zookie400

    Zookie400 Active Member

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    alcohol isnt bad, its just a different animal and you need to prepare for it....its coming!

    i will say this, alcohol requires much more fuel to achieve stoich......so there goes any fuel economy you had. when they switched from MTBE to 10% ethanol my mustangs mileage TANKED!

    adding more alcohol to my fuel is fine by me....if they lower the price!

    alcohol also runs much cooler and increases the knock resistance, so running 87octane with 10% ethanol should be FINE in one of these bikes.

    i was able to run the 87 alky fuel in a 12.5:1 compression race engine (with much more aggressive timing than our bikes) with no pinging. if you cant run it in one of these bikes, you are probably too lean.
     

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