Fuel Grade for a 990

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by MIghty, Feb 27, 2012.

  1. MIghty

    MIghty Been here awhile

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    I searched the forums and could not find any clear answer. What fuel grade to use on a 990? KTM recommends 91 or better. But I want to know if 89 will be fine for everyday full up's? I want to run 89 most/all the time but not sure if I should. Any experiences?

    Thank you in advance.
    #1
  2. AdvGa

    AdvGa Long timer

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    On my '06 950, I have been running usually 89 or high test fuel with No Problems.

    I limit my fuel sources generally to Top Tier Fuels:

    http://www.toptiergas.com/retailers.html

    Helps with quality control and the odds are better with High Test with little or no Ethanol to mess things up.

    Here's link to what they looked like:
    http://www.advrider.com/forums/showthread.php?t=741228

    <TABLE id=post17289899 class=tborder border=0 cellSpacing=0 cellPadding=4 width="100%" align=center><TBODY><TR vAlign=top><TD style="BORDER-BOTTOM: #575757 0px solid; BORDER-LEFT: #575757 1px solid; BORDER-TOP: #575757 0px solid; BORDER-RIGHT: #575757 1px solid" class=alt2 width=175></TD><TD style="BORDER-RIGHT: #575757 1px solid" id=td_post_17289899 class=alt1><!-- message -->

    [​IMG]


    My Carbs at 12k miles with Top Tier Gas & Periodic Gas Treatment.
    </TD></TR></TBODY></TABLE>
    #2
  3. bluesurf

    bluesurf en dos ruedas

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    Do you have connection under the seat disconnected or not?

    I don't recall reading this in my '06 950 manual, but reading the '10 990 manual shows that the connector is only recommended to be disconnected, with 89 fuel being used, for a single tank full....could be KTM lawyers at work, or ??
    #3
  4. MIghty

    MIghty Been here awhile

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    The problem is, every gas station that I know of around here uses up to 10% ethanol, every grade too. Not exactly sure how much. But I do know in winter the entire state changes to "winter gas" not sure what that means. Maybe another reason to hike gas prices.
    #4
  5. AdvGa

    AdvGa Long timer

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    I keep the Wires Connected but with a Switch I added:

    http://www.advrider.com/forums/showthread.php?p=11704904#post11704904

    Unless the Octane is REALLY Low like out of Country... it stays connected with no need to retard the timing to compensate for lower Octane.
    #5
  6. fierostetz

    fierostetz Been here awhile

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    why bother running the risk of lower grade gas? it should only amount to what.. a dollar, a dollar fifty per tank?

    serious question!
    #6
  7. AdvGa

    AdvGa Long timer

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    Here are some more details regarding the Octane in KTM from HOW:

    http://ktm950.info/how/wotf/wotf.html

    Low Octane Plug: The LC8 engine in the 950/990 KTM Adventures and Super Enduros line have an 11.5:1 compression ratio. It is designed to run on 95 RON premium fuel. The equivilent octane in the USA is 91 octane (RON+MON)/2. KTM thoughtfully provided a wire under the seat that can be disconnected when the high octane stuff isn't available. It causes the ECU to select a less aggressive ignition advance curve to prevent preignition. It is supposed to be good for down to 80 RON (77 in the USA).
    [​IMG]
    KTM specifies that only one tank of low octane fuel be used at a time. ie: this is supposed to be for emergency use only. Not for a way to run less expensive gas as a routine.
    #7
  8. Rixxy

    Rixxy Been here awhile

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    Hey guys,

    Been getting a fair bit of use out of th Low Octaine plug in India and Nepal, now come over to Laos and using it for the 91 fuel but am i right in thinking i dont need to?

    Also i'm finding the bike is running a little hot at slow speeds 1,2,3rd gear stuff, could this be something to do with it?

    Cheers,
    #8
  9. Grizzz4440

    Grizzz4440 Over the Hill (Wild Bill)

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    I've been running my 07/990 on low octain fuel sense new , with a tank of high octain every now & then. Wire has been disconnected for at least 10,000miles; I've got 19,000 on her now with NO problems.While on a trip over in E. Oregon a few years ago, my friends were riding 950's & all we could get was llow octain fuel.They could hardly get there 950's to start. Told them to pull the connection under the seat, NO MORE PROBLEMS. my 2cents Grizzz.:evil
    #9
  10. MIghty

    MIghty Been here awhile

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    I don't think so. I've read the 990s do run a little hot while in traffic or going slow. So I'm guessing it's normal. I could be wrong.
    #10
  11. DSM8

    DSM8 Where fun goes to die....

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    The 990's out of the box are very lean and at slow speeds run very hot.

    Mine used to hit 5 bars in no time stop and go traffic with the fan running constantly.

    You have to change the fuel curve to richen it up to alleviate the problem.
    Or switch to carbs.

    I did the latter.
    #11
  12. AdvGa

    AdvGa Long timer

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    Just for everyone's clarification, on the 990, aren't there 10 Bars Max?

    7 Bars on a 950, where 4 is the Normal Operating Range and the Fan comes on at 5 Bars..
    #12
  13. Kelvininin

    Kelvininin Been here awhile

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    The KTM engine is a high performance engine, with high compression and a pretty aggressive timing curve. KTM would not have gone through the effort to install the feature to retard the timing for no reason at all.

    The higher octane rating the greater the fuels resistance to burn the lesser the chance to induce premature detention or knocking. The high octane fuel is cheap insurance to minimize or eliminate knocking. In most cases with street riding conditions, in cooler weather, at or near sea level, with minimal stop and go, you are probably ok with mid grade fuel but in warmer climates or in the mountains, or in a lot of stop and go, you are better off protecting against knock with the higher grade fuel.


    For what its worth I see a lot of stop and go traffic in Seattle, and because of that I run the dual fans, lower temp thermostat and always run premium.
    #13
  14. rallyreplica

    rallyreplica out and about

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    #14