What Octane Fuel (R+M/2) do you use in your bike?

Discussion in 'The Garage' started by BikeMan, Apr 30, 2013.

  1. Tripped1

    Tripped1 Likely Lost.

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    http://rennsportsystems.com/letstalk-2/gasoline-detonation-twin-ignition/

    Either way he is right. I remember flashing chips for camaros and such in high school, you started 15* before TDC with the ignition and bumped it up by degree, the couple dual plug bikes I've plutzed with (a Ducati and a Harley) were both running like 3* degrees before TDC on timing at full tilt.
    #41
  2. opmike

    opmike Choosing to be here.

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    Good stuff on that Rennsport page. Thanks for the link.
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  3. foxtrapper

    foxtrapper Been here awhile

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    I would have thought it was glaringly obvious.
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  4. BikeMan

    BikeMan smoke, drink, screw, ride

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    its a more complete burn is the truth of the matter. hence the reduced timing required. but its not a quicker burn. even with dual plugs and domed pistons the burn is still not as complete or quicker as u call it, as a single plug located in the middle of the cylinder using flat top pistons. per rennsport link. IMHO, the big advantage of dual plugs is internal cylinder heat dissipation.
    #44
  5. joexr

    joexr Banned

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    I'm not interchanging more complete and quicker dumbass. It was in Rennsports writing. If the plug isn't in the middle two IS a QUICKER burn than one.:dealHence , less ignition advance is needed to accomplish almost the same thing.:fyyffSo what's your next thread going to be , what oil do you use?:rofl
    #45
  6. LuciferMutt

    LuciferMutt Rides slow bike slow

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    87 in both. The 250 has an engine that was designed in the early 80s...it's fine on the cheap swill. The VFR is pushing 18 years old herself...no reason to use the higher octane stuff in that either.
    #46
  7. anotherguy

    anotherguy Long timer

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    And to stir it up a bit high octane no longer has to mean a slow burn. Fuels are tailored to the application now including the need for a fast burn with high RPM large bore engines. And throw some heat management into the mix.

    VP used (R.I.P. :cry )to make a fuel called MR8 for high RPM 2 stroke GP bikes. It was 106 motor octane and evaporated fast and burned even faster. Better living through chemistry. You could throw tons of advance at it w/o any detonation. When you tune for X amount of deto events per mile as acceptable a good fuel is paramount to success.

    And then there's squish action and MSV. :D
    #47
  8. bikefreak47

    bikefreak47 Adventurer

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    Something not mentioned is elevation where vehicles are operated. I've always been led to believe that octane demand can be reduced by one point for every 2,000 feet of elevation. In my case, living at 7,200 feet I can safely knock off over three points of octane in my vehicles. Most run fine on 86 and in the higher compression vehicles I run 88 octane instead of 91.
    #48
  9. Dust_

    Dust_ Adventure Dreamer

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    95, which is the lowest here in my country. We do have 98, but I don't even bother :evil
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  10. joexr

    joexr Banned

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    Our octane ratings are different numerically. Your 98 is about the same as our 93.
    #50
  11. k-moe

    k-moe Long timer

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    I stopped for gas the other day and found this:
    [​IMG]
    Y'all can fill up with some of each, or make your own custom blend.
    Anybody need 88.33 octane? :rofl
    #51
  12. Dust_

    Dust_ Adventure Dreamer

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    Hum... makes sense, so I guess I fuel up with 91? :1drink
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  13. joexr

    joexr Banned

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    The pumps at our 7-elevens are like this , but everywhere else it's 87,89 and 93.
    #53
  14. Firemanmike69

    Firemanmike69 Been here awhile

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    [​IMG]
    Enough said
    #54
  15. joexr

    joexr Banned

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    There's a place here that sells 110 & maybe 100 or something , but it's not a road fuel so you aren't allowed to put it directly into a vehicle , you have to pump it into a container. Gulf used to have a leaded road fuel. It would crap up your sparkplugs though.
    #55
  16. vicmitch

    vicmitch Been here awhile

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    87 in both bikes


    2001 Victory Sport Cruiser
    2012 Suzuki V-Strom 650
    #56
  17. M3-SRT8

    M3-SRT8 Been here awhile

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    I was speaking about the engine in stock tune only. Period. (LOL)
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  18. DesmoDog

    DesmoDog Desmo's my dog

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    More complete burn, in less amount of time.... but it's not quicker?

    How do you more of something in less amount of time without doing it quicker?


    From Rennsport
    "Porsche’s hemispherical air-cooled heads are well known for poor swirl characteristics and the bigger bore engines are quite detonation prone at 9.5:1 and above.

    The water-cooled 4-valve heads used in the 996/997, Twin-Turbo/GT-3 and Boxster/Cayman engines have a centrally located spark plug that gives better and more thorough combustion with excellent swirl, without the need for twin-ignition."

    From what I can tell they're comparing single plug heads in both cases here. And they've changed more than just plug location. Swirl is a big part of the equation.

    Here's what I found in the Rennsport link about cooling:
    "The offset-plug position on a 911 delays the combustion process. By installing two spark plugs per cylinder, you will increase the acceleration of the ignition sequence. This can reduce the required advance by 10 degrees or more thus lowering cylinder head temperatures. "

    Nothing there about the plug dissipating heat. They attribute the lower cylinder head temps to timing. If heat dissipation was the biggest advantage to another plug, I would think they'd mention it somewhere?
    #58
  19. k-moe

    k-moe Long timer

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    I believe he's referencing the spark advance, not time spent burning.
    #59
  20. nbsdave

    nbsdave Been here awhile

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    it does not in the real world, only in textbook situations (on paper and before moisture absorbtion)
    the attraction of moisture by the ethanol actually lowers the octane rating in real world usage (in your tank)
    #60