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Thread: Octane Question

  1. #1

    Octane Question

    Is anyone using low octane fuel in their wetheads? I was riding with someone last week who only uses low octane in his K1200. I know it's a different engine but I wondered if anyone ever gave it a try on their new wethead.

  2. #2
    Debbie's Servant Lee's Avatar
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    The manual calls for 89 AKI. If you can't find 89 it wont hurt to use 87 once in awhile.
    The manual say if you use 87 AKI all the time the bike needs to be reprogrammed.
    Lee
    2016 R1200RS
    MOA # 30878
    Past BMW Bikes: 2011 K1300S, 2003 K1200RS, 1991 K75S, 1987 K75T, 1984 R100RT

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    Quote Originally Posted by collesidis View Post
    Is anyone using low octane fuel in their wetheads? I was riding with someone last week who only uses low octane in his K1200. I know it's a different engine but I wondered if anyone ever gave it a try on their new wethead.
    https://plus.google.com/+JohnSherman2/posts/AmHm7Qj4rk6

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    I use low octane fuel during winter cold months but when I do I don't run engine RPMs higher than 4.5k. Summer higher octane then I will take RPMs to rev limiter stop. Just my theory for my 2016 R1200RT wet head.

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  5. #5
    Registered User dabubba's Avatar
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    Higher octane will yield better gas mileage, so in my book it's almost a wash and certainly not worth possibly damaging a very expensive engine. Pay for the high octane if it's available.
    Mike Gray #103649
    2000 K1200LTC
    2014 F700GS
    2016 R1200RT

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    Registered User lkraus's Avatar
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    Quote Originally Posted by dabubba View Post
    Higher octane will yield better gas mileage, so in my book it's almost a wash and certainly not worth possibly damaging a very expensive engine. Pay for the high octane if it's available.
    My Hexhead has knock sensors so I'm not worried about engine damage. Using low octane does slightly lower gas mileage and power, noticeably reducing my passing acceleration. The price difference is not significant in the grand scheme of things, so I use premium exclusively and enjoy the power - that's a part of why I bought the bike.

    I assume the Wethead has some sort of knock management system, but have not heard any description of how it might work. I understand the knock sensor has been eliminated, so without knowing IF the bike is protected against pre-ignition, I'd play it safe and use the specified fuel.
    Larry
    2006 R1200RT

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    Quote Originally Posted by johnesherman View Post
    I use low octane fuel during winter cold months but when I do I don't run engine RPMs higher than 4.5k. Summer higher octane then I will take RPMs to rev limiter stop. Just my theory for my 2016 R1200RT wet head.

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    Can you explain your thinking in that decision, as it really makes no sense to me.
    The danger of lower octane fuel is pre-ignition, or knocking. Most likely to occur at lower revs (not higher), in hotter temps (not winter), and under higher load (carrying mucho weight or ascending serious grades.
    Ride Safe, Ride Lots

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    Well, answer to your question: octane, RPM, & winter, my theory applied. No high RPMs with lower octane fuel used during cold winter riding.

    See generally,

    https://www.hemmings.com/blog/2014/0...-priced-fuels/

    http://www.faqs.org/faqs/autos/gasol...section-1.html

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  9. #9
    Quote Originally Posted by dabubba View Post
    Higher octane will yield better gas mileage, so in my book it's almost a wash and certainly not worth possibly damaging a very expensive engine. Pay for the high octane if it's available.
    The question is higher than what? My GS is rated for 89 aki. You might get some knock using 87 but you do NOT get better mileage or anything else from going to 92. The BMW engineers built the engine for 89 and state you can use 87 in a pinch. 92 was never in the game. If you want better mileage get non-alcohol, straight, old fashioned gas rated at 89.
    Old But Not Dead
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    Quote Originally Posted by johnesherman View Post
    Well, answer to your question: octane, RPM, & winter, my theory applied. No high RPMs with lower octane fuel used during cold winter riding.

    See generally,

    https://www.hemmings.com/blog/2014/0...-priced-fuels/

    http://www.faqs.org/faqs/autos/gasol...section-1.html

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    still leaves me asking that proverbial question "why bother with either limitation- lowered rpm and/or lower octane? to save a few pennies? I know on my '16GS, keeping it under any arbitrary rpm (other than redline) is not an easy task... and certainly not when it's just getting into the fun zone of above 5K.

    i guess that's why they make bagels, ice cream, pie, donuts and pizza in all kinds of flavors... to each his own.
    Ride Safe, Ride Lots

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    Quote Originally Posted by bikerfish1100 View Post
    still leaves me asking that proverbial question "why bother with either limitation- lowered rpm and/or lower octane? to save a few pennies? I know on my '16GS, keeping it under any arbitrary rpm (other than redline) is not an easy task... and certainly not when it's just getting into the fun zone of above 5K.

    i guess that's why they make bagels, ice cream, pie, donuts and pizza in all kinds of flavors... to each his own.
    The simple answer: Use the BNW OEM suggested octane fuel minimum rating for entire RPMs use and enjoy the ride

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    John Sherman
    Tacoma WA USA
    2016 R120RT
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  12. #12
    Registered User kioolt's Avatar
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    I was taught many years ago that you should use the lowest octane gas that the engine will not pre-detonate with. This would provide the best fuel economy. This was before knock detectors, ECU's, fuel injection, etc. I was able to find the following to support this.

    "Use the recommended gas for your car. Going lower than the recommended may reduce fuel economy as the engine may have to retard timing to avoid detonation. Going higher than recommended won't help as your engine is unable to take full advantage of it, as well as the fact that higher octane fuels actually contain slightly less energy (they just offer a more controlled burn that higher compression engines can take advantage of)."

    Even more information.

    http://www.fueleconomy.gov/feg/octane.shtml
    Last edited by kioolt; 04-19-2017 at 03:47 PM.
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    Registered User BMARC153920's Avatar
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    Quote Originally Posted by dabubba View Post
    Higher octane will yield better gas mileage, so in my book it's almost a wash and certainly not worth possibly damaging a very expensive engine. Pay for the high octane if it's available.
    This is not true and has been proven study after study. Google is your friend....If it were true every single car manufacturer would call for super unleaded in every car to help epa mpg requirements.

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    Registered User lkraus's Avatar
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    Quote Originally Posted by BMARC153920 View Post
    This is not true and has been proven study after study. Google is your friend....If it were true every single car manufacturer would call for super unleaded in every car to help epa mpg requirements.

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    This needs some clarification. Using higher than specified octane does not improve mileage. But for some engines with high compression ratios like the R1200 in question here, using the specified higher octane DOES improve mileage, because that is the fuel the engine is designed to burn. Using lower than specified octane can produce knock, causing the ECU to change spark timing, reducing power and efficiency.
    Larry
    2006 R1200RT

  15. #15
    Registered User LFarling's Avatar
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    My 2015 LC RT calls for 93. Not sure where all these other numbers come from but 93 is what my bike runs.

    It is listed as this.

    Recommended fuel quality
    Super unleaded (max. 10 % ethanol, E10)
    89 AKI (95 ROZ/RON)
    89 AKI

    Where I live Super Unleaded is 93 10% corn, E10

    If I read it correctly it says the preferred fuel is Super unleaded. Then that the other 2 choices are acceptable substitutes.

    A RT WC has NO knock sensor in it. None! If you hear, or think you hear pinging, you probably are.
    Last edited by LFarling; 04-20-2017 at 02:51 PM.
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