Low octane fuel -Vs- Ignition curv?

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by bikeworm, Nov 24, 2004.

  1. bikeworm

    bikeworm Been here awhile

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    I have been running my bike on 92 since I got it. Board the other night, nothing new on Orange Crush I reverted to my owners manual and found a few paragraphs on setting the ignition curv for fuel less than 95 ROZ. Im sure this is to prevent pre-detonation? Other than racing fuel I haven't seen higher octanes available. According to the manual I should pull the plug to detune the bike. My clue and question to my fellow tread junkies is "ROZ"! The manual states 95 ROZ. I have no pinging and no intentions to pulling the plug. So how doe 95 ROZ compare to 92?
    Thanks :thumb
    #1
  2. Mike in Oregon

    Mike in Oregon Been here awhile

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    Bikeworm,

    Don't worry. Just run premium when you can; if you can't, unplug the wire under the seat to lower the ignition curve for motor. The "ROZ" is, I think how Europe rate their fuel octane. In U.S.A. it's called "RON"...I think. Our bikes are from Austria, and, as such the manuals talk about "ROZ" when mentioning octane. I believe the European ROZ converts to a lower RON number in USA-I.E. 95 ROZ is roughly 92 RON. Someone with degree in petroleum engineering pipe in!

    Just run premium when you can. When I first received my bike from dealer, they must have had regular unlead in , as bike DID knock on acceleration-loudly enough to be heard through earplugs. On that first tank of gas I did unplug the wire and bike no longer knocked. Has never knocked in 3000 miles on premium since, with wire pluged in.

    Also must report that my bike has had Zero problems in 3000 miles (early I know). I keep eye on coolant, but other than adding and ounce or two early on, bike is perfect. I use the 950 as my main form of transpo when ever I can-commute, weekly groceries, 120mph in Columbia Gorge in Oregon.

    Mike N.
    #2
  3. katoom_950

    katoom_950 Life, 2 short 4 traffic

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    To answer the first question I can offer this explenation src...;

    "Simply put, the octane rating of a fuel determines the propensity to explode. Simply put, the octane rating of a fuel determines the propensity to explode rather than simply burn when mixed with air and ignited. Exploding is bad. Burning is good. The higher the octane, the more resistant to exploding.

    If you are running too low of an octane for your motor, you will get
    pinging. Pinging in its extreme form is also known as detonation. The
    fuel/air mixture is igniting all at once and exploding instead of igniting
    as a flame wave. The resultant "bang" is very hard on the pistons, head,
    rods, and cranks.

    In an overly-simplistic nutshell, adjusting the ignition curve of an engine will usually advance the ignition timing, adjust the fuel/air ratio, and modify several other highly proprietary and secret things to increase performance. Among the main factors in detonation are (1) heat; (2) compression ratio; (3) octane rating; (4) fuel/air ratio; (5) ignition timing. Modifying any of
    these factors can either increase or decrease the propensity to detonate.
    Advance the ignition timing and you increase the potential to detonate.
    Retard the timing and you decrease the potential to detonate. You can
    balance these factors by modifying some to offset others. If you increase
    the fuel/air ratio and advance the timing, you can raise the octane and end
    up with more-or-less the same propensity to detonate as the non-modified
    motor. Alternately, you could lower the compression ratio, but this would
    cause a loss of horsepower and efficiency and undo all the gains of
    modifying the mix and the timing."​

    With the 950, disconecting the wire indicated in the owners manual will simply adjust the ignition curve for you and avoid the effects of a lower octane gas...

    For the second question, ROZ (Reguläre Octan-Zahl) is the German equivilant to RON (Research Octane Number) and although I do not know the differences between the two I am fairly certain 95 ROZ will equate to a 92 RON.
    #3
  4. bikeworm

    bikeworm Been here awhile

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    Thanks Mike & Katoom. The more I learn about this bike the more I love it. I have 1700 miles on mine and no problems either, but I have been changing all kinds of things, from the Canerostomy, and blanking plates, Remus mufflers, Sommer air box mod, straighter bars and now front shock mods. The bike just keeps getting better, I wish I could say the same about my riding!!! :rofl
    #4
  5. overlandr

    overlandr Dystopist

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    Found this on the web which may expand further - rather biased towards the US and couldn't find much on ROZ.

    Allan Martini wrote an excellent Explanation - especially for US customers:

    There is no difference between octane measurements in the US and Europe but the emphasis in specifing may be different. I will give a summary first and then some details There are four commonly used ways to measure and state octane values. These are:

    RON Reaserch Octane Number. This is the value commonly used by DG, Stemme, etc to specify an octane requirement. NOTE I don't have my DG manuals anymore and I haven't been able to find anyone here that has heard of ROZ, but I have the question still out to some of my friends in Chevron.

    MON Motor Octane Number. This value is determined in a different way. It is often considered to be more sensitve to changes in operating conditions and their effect on the engine than RON.

    AKI Anti-Knock Index. This is the number that is posted on the gas pump in the USA as "Octane". It is derived as (RON + MON)/2 In other words, an average of RON and MON values.

    RON is typically 8 to 10 points higher than MON. Therefor, the average is typically 4 to 5 points above MON and 4 to 5 poins lower than RON. Thus, a requirement for 95 RON gasoline should be met by 91 "octane" fuel in the US. This explains Gary Evans information.

    RdON Road Octane Number. Not generally used but mostly related to fine tuning fuel for racing engines.

    Some background: The term octane for fuel anti-knock qualities was developed, I believe, by General Motors in the early 30's. The RON is the percentage mixture of two gasoline components, iso-octane (C8H18) which has very good compression/antiknock qualities and heptane (C7H16) which has poor compression/antiknock qualities. If the mixture contains 80% iso-octane it is deemed to have an RON of 80.

    The test fuel is then burned in a single cylinder test engine with variable compression and rigid conditions of rpm, air temp, spark advance, barometric pressure, etc and the antiknock qualities measured. Any other mixture of hydrocarbons which has the same antiknock qualities will also be considered to have an RON of 80.

    MON is measured in the same type of engine using several changes in rpm, temp, throttle position, etc which make the operating conditions much more severe (and possibly more realistic) and the octane numbers are lower.

    RdON is measured in multi-cylinder engines, usually at wide open throttle, and usually on an engine dynamometer. The procedure is used to develope racing fuels.

    All that is probably more than you wanted to know, but I hope it helps.
    #5
  6. FarmerRick

    FarmerRick Long timer

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    In the US (and I believe Canada's CLC) the fuel at the pump is measured as (RON+MON)/2.

    ROZ is German Reguläre Octan-Zahl which translates to Regulation Octane Number. Hence, ROZ and RON are the same!

    The old 91 RON(ROZ) is equal to today's regular gasoline, with an octane number between 85 and 87 (RON+ MON divided by 2).

    91 RON = 87 (RON+MON)/2 (Regular) US Pump Octane Rating
    95 RON = 91 (RON+MON)/2 (Premium) US Pump Octane Rating

    So before you pull the wire, check and see how the octane rating is calculated at the pump...

    Hope this helps!!

    Rick Mathis
    Franklin, TN
    #6
  7. katoom_950

    katoom_950 Life, 2 short 4 traffic

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    I agree but I am of the impression that in Germany/Europe the calculation is not taken to RON+MON/2 but simply read as ROZ(RON) so the figure will differ slightly to the 'average' figure derived from the US approach that gives you a PON (pump octane number).

    The problem stems from the fact you can have a variable between the RON value of gas and the MON value. Look at this link and it explains, seems there is a system of covering up a bad fuel in the US. You decide...

    Link
    #7
  8. HardCase

    HardCase winter is coming

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    This sounds right to me because all of the 'premium' around here (NW Montana) is 91 octane and works great in the 950, no knocking whatsoever.
    #8
  9. Achange

    Achange New and Improved

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    My dealer suggested that I disconnect this wire when riding in the dirt to keep the back tire from loosing traction so easily, even if I'm running on Premium. Has anyone tried this? Can you think of any adverse effect on the engine if you run the bike with the wire disconnected while running with the higher octane fuel?
    #9
  10. Desmofan

    Desmofan Been here awhile

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    I just finished a 1600 mile run in Baja, and most of the time (500 miles in dirt) the gas was out of barrels (not sure WHAT octane that was), barrels and through a chamois :huh , and PEMEX with "87" octane usually (more like 84). I heard a death rattle a couple of times, pulled the plug, and no more worries. I also was careful not to lug the engine. The Mex premium is as high as 92 (only in the Turista zones), and according to a Baja 1000 pal, it is actually higher due to lack of MTBE crap etc.

    Anyway, the moral is: the octane wire is cool, it does work, and never pass a gasp stop in Baja :D
    #10