Activating Low Octane Ignition Curve

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by stephenws, Oct 25, 2008.

  1. Trail Flyer

    Trail Flyer Road ""closed""?

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    I run my '04 950 with the low octane leads disconnected almost all of the time and usually run midgrade gas (in CA, I think it's around 89 octane). I tried running with the leads connected and used premium but never noticed ANY change whatsoever in performance or fuel economy (I always get about 140 miles before the reserve light comes on- which is crappy). I've never heard any pinging. Even with the leads disconnected I have no problem pulling wheelies in 2nd and sometimes 3rd gears, and with all the power I want I see no reason to run the better fuel. :1drink
    #21
  2. abruzzi

    abruzzi Long timer

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    Wikipedia has a good explanation of octanes. THere are two different typs of measurements RON and MON (I'm assuming ROZ is the same as RON.) USA uses the average of the two. You've probably noticed that pumps mention (R+M)/2. RON 95 genrally equates to 90 (R+M)/2.

    Geof
    #22
  3. tahoeacr

    tahoeacr Long timer

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    While on the dyno today I decided to unplug and see what we got. Loss of a couple HP below about 6k but peak HP was not that far off. The VERY SCARRY part was it leaned out the A/F readings. Way out.
    #23
  4. Vicks

    Vicks gets stuck in sand

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    does that mean that with the low octane plug disconnected, the engine runs hotter ?
    #24
  5. Bok Befok

    Bok Befok Been here awhile

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    hey neighbour, ive been wondering how good the 10% ethanol is in the fuel. would there be any problems if using the fuel with ethanol?
    #25
  6. Helmet Head

    Helmet Head Have bike, will travel...

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    A little off-topic, as 'bad gas' and octane have nothing to do with each other, despite what oil companies would like you to think. That is, it's perfectly possible to have excellent quality low-octane fuel and total crap high-octane fuel. Octane is simply a measure of the temperature at which the fuel spontaneously combusts; it has nothing to do with energy contained in the fuel or how clean the fuel is.

    But, since you ask... ethanol is total shit IMO. It's highly hydrophilic, so it attracts water at a much faster rate than pure gasoline. It has much more oxygen than gasoline, so it runs hotter. It also has less energy than gasoline (even though it is higher octane - showing that not only do octane and energy have nothing to do with each other, but they can actually have an inverse relationship in some cases), so you get lower mileage with it. It doesn't burn as cleanly, so it makes many engines run rough. I don't want to turn this into a political argument, but it's been pretty well proven that ethanol is being used purely to support the US corn industry and not because it has any advantage as a fuel. Even in terms of environmental impact, its effect is null on emissions, and a loss in terms of production. Again, it's shit. Since becoming universal here in New England, all of my vehicles have run worse and gotten lower MPG. I know for a fact it was the cause of surging and stalling on my BMW F650GS, and I suspect it is the cause of those symptoms in many EFI bikes.

    Ethanol! :becca :kboom

    Here's what I think of Congress, the EPA, etc. for letting this crap into our fuel supply... :fyyff
    #26
  7. Bok Befok

    Bok Befok Been here awhile

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    Thats exactly wut i wanted to know, thanks mate
    #27
  8. PHACTORYPHIL

    PHACTORYPHIL Adventurer

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    So what's the verdict? I' am hearing mixed reviews.. I've run all 3 American octanes from sea level to 10,000 ft without any problems and without activating the low octane ignition curve. I'm thinking about installing a switch just incase I get some really bad fuel or am I just wasting my time?
    #28
  9. tahoeacr

    tahoeacr Long timer

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    Don't think you have to sweat it. Yesterday I got stuck out in the desert away from any real gas stations. The only one had only 87 octane. I put 1.5 gallons in to get me back. My knock sensor didn't show any more knocks than with 91. I did not disconnect the octane switch. This was at about 4,700'.
    #29
  10. lakecntyrider

    lakecntyrider Adventurer

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    This happened to me on a trip last month after switching to low octane, so searched on the site to see if anyone else encountered this. What does it mean that it's "normal"? Does anyone know why it is raised?
    #30
  11. crashmaster

    crashmaster ow, my balls!

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    Its normal because everyone (I think everyone) will get those codes that run the low octane curve on a 990.

    My biggest issue with low octane curve is that when at high elevation, over 10,000 feet, once the engine warms up it will settle into a 1000 rpm idle and can be very difficult to start warm without adding a little throttle.

    I am currently in Bolivia and have been running the low octane curve since Colombia.

    Here in Bolivia at 14,000 to 16,000 feet, the bike will not hot start unless I add throttle.

    It would be interesting to see what tahoeacr thinks about running the low octane map. What is worse? The lean condition of the low octane curve, or the detonation of the standard curve? :scratch
    #31
  12. ktm_pilot

    ktm_pilot n00b

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    I am a newbie to both adventure motorcycling and AdvRider. I have read through this thread and have seen several posts over several years on 950's and 990's, so just want to see if I understand correctly for my specific bike:

    I live in the interior of South Africa (+/- 4,500' elevation and above) and we get mostly unleaded 93 RON fuel, while in the bigger cities but less common in smaller towns 95 RON is also available. The owner's manual of my 2011 990 Adventure says however that only 95 RON (I believe the USA equivalent is 91 PON) can be used, and if less octane than that is used the under-seat connector must be disconnected "for one tank only". This can be a problem riding in rural areas around here.

    So, my questions are therefore:

    • If I want to fuel with 93 RON fuel can I ignore the user's manual and do so without disconnecting the ignition curve connector, or must I take it seriously to avoid engine damage?
    • What does "for one tank only" in the manual mean - is this "one tank only in the entire life of the bike" or is it "one tank only before again returning to 95 RON fuel"? Can I then mix 95 and 93 fuel, or must the tank be drained of 93 fuel before 95 fuel is again added?
    Thanks for your answers, ride safely.
    #32
  13. BroodRooster

    BroodRooster Adventurer

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    By the way, I have a 2003 adventure with carbs, but I cant find an ignition curve cable or anything under the seat. Is this feature only on the 990's?
    #33
  14. Alejo

    Alejo Been here awhile

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    I can´t explain why (mechanically speaking) but it is normal, I use the mode (disconnected) to ride technical stuff since the bike has less power and every time I disconnect the wire the FI code starts to blink blink but if you ride it for a while it goes away.

    No problems at all after re-connected the wire.
    #34
  15. 990adv

    990adv Adventurer

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    I have Lexx pipes and the R map on my 2010 990 and have had some weird ping every now and then along with the jerky throttle. The bike runs like a beast with wide open throttle. I cant even ease through my neiborhood without holding my hand on the side of the throttle. So While I was doing some maintenance I decide to unplug the curve connector and try it. I have never seen anyplace that sells 95 octance gas around me anyway. I notice right off that the jerky throttle was completely gone and the drivability was vastly improved, like a completely different bike. I didnt notice any real power loss and no error lights. I will try and put some more miles on and see what happens but for right nowIi am very happy with the change.:D
    #35