Sherco Gas Mix. 80:1???

Discussion in 'Trials' started by Metrotexual, Jan 31, 2011.

  1. Metrotexual

    Metrotexual Been here awhile

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    Guys. or er.. ladies...

    I just picked up an 02 2.9. Thing is, the manual that I have states the mix should be 80:1. That seems really lean to me. Any reason why this is so? i was hoping to pour the same mix I'm using in the KTM 300, which is a 50:1 Motul 710 mix.

    Thanks.
    #1
  2. BorisTas

    BorisTas Ageing Adventurer

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    Howdy Teulfel,

    Have had 3 290's , an 00 an 07 and my current 09, various ones have recomended 50:1 on the sticker but I've always run 'em at 80:1 and they still drip oil out the pipe, some I know use 100:1 so presuming you are TRIALS 'ing them and not MX racing pick a fig between 50and 100 and go for it !!:lol3
    Motul is agood'un so why not tip in 2ltrs of your Katey mix and 1ltr of fuel and you've got 75:1 :evil

    BT
    #2
  3. Brewtus

    Brewtus Buffoonery, Inc.

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    Take Boris' word for it. 80:1 is more than OK for trials use.
    #3
  4. Metrotexual

    Metrotexual Been here awhile

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    Awesome Gents. Thank you!

    I've rewarded your kind reply with a photo of my scoot. It's an 02, and i paid two thousand for it a while back. Now i have made the time for trials and some training.

    [​IMG]
    #4
  5. Brewtus

    Brewtus Buffoonery, Inc.

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    Sweet scoot. Very nice! :thumb
    #5
  6. BorisTas

    BorisTas Ageing Adventurer

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    Always liked the chrome frame models . very nice !!

    Since we're doing the picture thing

    2000

    [​IMG]


    2007

    [​IMG]


    2009 R

    [​IMG]


    Hope you have as much fun with yours as I have:rofl

    BT:D
    #6
  7. Brewtus

    Brewtus Buffoonery, Inc.

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    If I must.....

    [​IMG]


    [​IMG]

    All three of my Montesas, the 314, 315, and the 4RT. Enjoy! :D
    #7
  8. Sting32

    Sting32 Trials Evangelist

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    Teufelshunde: and anyone else getting a trials bike! Please note this about oil ratios...

    80:1 If you use what most of us state & do ourselves, you MUST agree the following is true.
    {ALL}

    A: this is for water cooled, newer TRIALS bikes!
    B: EVERYONE assumes you are riding trials! or practicing trials, not anything else.
    C: Using good quality oils, I recommend fully synthetic.

    If you do something we cant forsee, like enter some "last man standing" or
    enduro cross, or decide to race to town some 45 miles away, running your
    Trials bike that way, and "if" somehow stuff goes bad, Don't come back
    and yell at all of us here.

    In trials, if you think about what the engine is doing for "every minute"
    while you "ride it" you would notice that MOST trials activities are done at
    idle. I'd venture to say less experienced riders it might be more than 80%
    of the time. & that is a low conservative estimate. On the other hand your
    MX/enduro/street rocket is the opposite, it is allowed to idle probably less
    than 20% of the time you are riding. If you "race" on a trials bike, & mix at
    80:1, nobody here is going to be shocked that it burns something up, I
    would be suprised but still, you are now warned, and YMMV, :thumb
    #8
  9. BarkSlayer

    BarkSlayer Been here awhile

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    The 80:1 premix ratio is actually RICHER than what you'd imagined - say 40:1 or 50:1. Keep in mind that the engine runs on gasoline - not oil, so a ratio of 80:1 means more gas (richer) for every drop of fuel it ingests.
    #9
  10. Sting32

    Sting32 Trials Evangelist

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    Bark, please...
    in this whole context, the richness is oil to gas, not gas to air, PERIOD.

    We're exclusively talking about the ratio between gas and oil, a product you have to concoct to operate 2 stroke engines in our trials motorcycles with 2 stroke combustion engines.

    What you are refering to is jetting and carb functions at some engineering level which was done before the bike's carb was picked and used in production.

    FWIW, there was a study done in the 70's or 80's published and is or was on the internet, and I dont have the link anymore, but the gist was except the too extremes (no oil and way too much oil) differences only acounted for infitessimal changes on an engine running wide open, IE: racing or weed eating. the study showed and the engineers figured the rich oil mixture helps ring to bore sealing over the gains and losses due to friction on same engine when less oil was use and the engine got more "fuel per atomised droplet" or the "richer" mixture you are refering to.

    as far as 50:1 through 100:1 there is hardly any affect what so ever on a trials engine, that "oil to gas mixture not specific" carb tuning as suggested for your altitude, on engines which see wide open for bursts lasting well under a minute at most, in any type of trials competition mode of use.

    What you will find though, when you have more oil in a trials bike than it can use and "burn" you fill the exhaust system with oil, see more "smoke" out the exhaust, than you really need to. take that $200 muffler on any trials bike, that someone engineered to be as light as possible, yet durable enough to last (gasgas will get there someday, lol) and then fill it with 3-5 lbs of extra oils, seems senseless to me, but that is just me maybe.
    #10
  11. BarkSlayer

    BarkSlayer Been here awhile

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    :huh

    All I'm referring to is the simple fact that the whole "rich/lean discussion" as it pertains to two-stroke premix ratios and carburetion is one of the most widely misunderstood concepts in motorcycling.
    #11
  12. trailer Rails

    trailer Rails Long timer

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    I think you are making this more complicated than it needs to be. Just so I understand you correctly. You are saying 50:1 is 98% fuel and 2% oil. So 80:1 is 98.75% fuel to 1.25% oil. So in essence you are correct, there is more fuel and you might be able to call it richer when refrenced to the Fuel air mixture.
    #12
  13. Sting32

    Sting32 Trials Evangelist

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    Again,
    I hate to see NEW trials riders get confused about rich or lean oil mixture becuase
    you want to theorize on the rich/lean fuel_with_oil_ droplet_size to air Mixtures theory,
    which is NOT what this thread is about. (did you read the subject line?)

    We BOTH know dang well, that a dirty air filter is a bigger concern and effect on
    lean/rich Air to Fuel ratios, than droplet sizes of premmixed gas and how it could affect FUEL to air ratios...

    Most of us change jets, and move the needles to fix "lean/rich combustion" conditions.
    In this thread about OIL TO GAS MIXTURES RATIOS we use and RECOMMEND,...

    You are going to have to accept 2 things to be virtually true:

    1, 99 out of 100 riders will NEVER adjust rich/lean combustion setting by changing fuel to OIL ratios

    2, that trials MFG's have already pretty much tackled the rich/lean
    combustion settings by picking the carb, then recommending the correct
    jetting, needle and screw settings, all based on a fair range of
    recomended oil/gas ratio's for MOST RIDERS, for your altitude through a
    fair amount of testing. Yes there is flexibility, jets, needles, adjusting
    screws etc.

    We accept it, and know in some aspects there are alternatives, like
    different carb MFG that do slightly better or Worse in giving AIR/FUEL
    mixtures at different Velocities of demand through the carbs. (some carbs
    work better off idle, some better at high to highest RPM, as well as jetting
    I know, can affect it through all different ranges. :thumb

    So, lets leave those thoughs you added above, in your "lean/rich air
    mixture biases effects from oil/fuel mixtures... (a Physics & engineering study)."
    Which of course is a thread that you have not started YET

    In such thread, I would argue that the amount of oil per droplet of air fuel
    mixture delivered via carb, in a TRIALS engine {AND operated and Dyno'd
    as a trials engine} has 1/100th of the already infinitesimal affect on rich/lean fuel to air mixture.

    I might be wrong with that arguement, it has been a while since I last stayed in a Holiday Inn Express... :>
    #13
  14. BarkSlayer

    BarkSlayer Been here awhile

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    Sting, my friend...lighten up. There's nothing going on here that warrants a tirade. But in all fairness, if a rider is new to two-stroke tuning, wouldn't you agree that he has a much better base to learn from with good information going in? 80:1 is a richer premix ratio than 50:1. If your reality differs...I can't help you. It's all good.
    #14
  15. BarkSlayer

    BarkSlayer Been here awhile

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    Yes, exactly...80:1 is richer than 50:1. That's all there was to it.
    #15
  16. trailer Rails

    trailer Rails Long timer

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    The problem is that it is not information that anyone really needs to concern themselves with. There are many other things that would have a far greater effect on your fuel air mixture.
    In this conversation we were discussing richness of fuel in relation to oil not richness in relation to fuel and air. You need to go back and read the first part of the conversation.
    #16
  17. BarkSlayer

    BarkSlayer Been here awhile

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    My bad. Won't happen again.
    #17
  18. Sting32

    Sting32 Trials Evangelist

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    Bark,

    to be fair and clear (I think I can speak for most of us that srtive to answer questions regularly...
    I am/I think we all are glad you are willing to help out with information, I
    didnt mean you to think I ranted. all I was wanting to do is keep the
    information simple and to the point asked.

    I/We can only hope you understand that.

    I am in "User support" more or less, for a living... Sure it is computers but I
    help many fellow riders as well... so yeah, I am more sensitive to
    "confusing" information, and confused users that eventually call for help,
    then explain that they "read that..." which is usually good information, but
    didn't apply to the situation at hand, before they blew up the computer,
    or rear tire tire, or smoked a 2stroke on a lean mixture of oil to gas. or in
    my daily cases, lost critical files.​

    and as one ADV member and rider to another we've already read/heard
    from a new trials rider that missed the information all together, ran his 2
    stroke without oil... :cry
    #18