Favorite Premix Oil and Ratio

Discussion in '2 smokers' started by craydds, Mar 26, 2013.

  1. CharlieT

    CharlieT old school

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    Your self-righteous and over whelming arrogance is hilarious. Tell us again why you are the only one in the universe who believes this, when a factory GP tuner disputes your claim?? When no other reputable 2-cycle tuner or oil manufacturer has elucidated this claim? It is so kind of you to share this tidbit of knowledge based *only* upon your personal experience. Or did you actually flow test the jets to determine this? If so I would have thought such a finding would have been worthy of publication

    I'm am indeed very surprised that you are even aware that the word "wrong" exists in the English language. But on the other hand, I'm sure you use it all the time, telling the whole rest of the world they are wrong and you are right

    It is not that it does change the flow, but its effect is so minimal that a jet change is unnecessary. Now if you go from an injection unit to a pure castor based premix and its 20degF out, you might be onto something.

    Or as in another example. Does humidity affect jetting....most certainly does, however if the humidity changes from 70% to 72% its effect is not going to be sufficient to warrant a jet change. Of course that's just based on my personal experience. :)
    #81
  2. Mr. Carts

    Mr. Carts Been here awhile

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    So do I use Blendzall at 20 to 1 or 24 to 1 in my IT465.
    #82
  3. craydds

    craydds Long timer

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    Again, from what I remember from my past (way too many beers ago) jetting was based upon AIR DENSITY - humidity, temperature, barometric pressure at that particular hour, sheesh - but these were professional tuners for RACE bikes on race day. I was just trying to make it around the track without crashing. Now, I only want to go for a ride in the desert (I still have that competitive racer stuff flowing through my blood, can beat my young sons, they think their old man is crazee).
    #83
  4. Twin-shocker

    Twin-shocker Long timer

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    Unfortunately unless the laws of physics have changed recently, increasing the viscosity of a liquid will reduce its rate of flow through a carb jet of a given size.

    How you feel clarifying that fact in clear and concise terms is arrogant or hilarious, seems to suggest that you may well be just another web warrior with no first hand experience of tuning 2T motors themselves?

    I wont bother to go into the area of changes to carburetion required to suit differing atmospheric conditions, as you appear to have problems grasping the basics, and seem to have been blinded by ridiculous advertising blurb, and test data produced 40 years ago!
    #84
  5. Twin-shocker

    Twin-shocker Long timer

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    Quite so............humidity does have a minor affect on the jetting required on a particular day, but the main determining factor is air pressure. I guess most serious racers running 2T bikes today, will have weather stations, and previous data related to best set up for differing conditions, which will make set up far easier than back in the day.
    #85
  6. Twin-shocker

    Twin-shocker Long timer

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    Yes if you are running flat out almost continuously, or are using the IT motor for road racing. If not then I would suggest a fully synthetic pre mix only oil at 40:1 for competition use, or the same at 60:1 for recreational riding. If you have been using 20:1 for some while and the bike runs well, you may find a need to reduce jet sizes to work best with reduced amount of oil.
    #86
  7. anotherguy

    anotherguy Long timer

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    I extend an invitation to ride my unresponsive,dull feeling YZ465 fueled on VP U4.4 @ 32:1 to you Twin Shocker. If after that you contend it's unresponsive and dull feeling I'll let you tune that out for me.
    #87
  8. lrutt

    lrutt SILENCE.....i kill you

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    All this is just metal masturbation. For 90% of the 2 smoke riders out there all this last ounce of tuning that might be obtainable by what you are describing is not practical. If you're running your old smoker to this high of level of tune, good luck.

    Me...I'll play it safe, run it a tad heavy on the oil and a tad rich on the jets so I don't sieze. Has worked fine for me since I started riding smokers in 1970. The limiting factor when I was racing was not that extra 1 hp i might get by tweaking mixtures, it was me!
    #88
  9. Twin-shocker

    Twin-shocker Long timer

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    If you are a play bike rider, then using more than the required amount of oil wont make much difference, other than the fact your bike wont run as well as it would with the correct amount.
    #89
  10. James Adams

    James Adams ɹǝsn uʍop ǝpᴉsdn Administrator

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    While true, this is negligible when talking about changing premix ratios. As others have pointed out, it is more important to consider that a higher ratio of oil to gas means that there's less gas per volume (much more significant than the slight change in viscosity), so you may need a larger jet. Of course, this will mean that you've also compensated for the slight increase in viscosity.

    If you boil down Jenning's article, his recommendation is that you err on the oil-rich side, as too little oil is worse than too much oil. If a good baseline castor oil premix ratio is 20:1, and 15:1 is slightly better, then it stands to reason that if a comparable baseline synthetic premix ratio is 60:1, then a 45:1 ratio certainly won't hurt.

    Personally, I use good synthetic 2T oil (Bel-Ray, Motorex, etc.) pre-mixed at about 40:1 in my CR480R riding trails and fire roads up in the mountains. Works for me and I don't really see the need to do anything differently. :dunno
    #90
  11. anotherguy

    anotherguy Long timer

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    Do you have empirical evidence to support that? By that I mean testing w/dyno charts. You make many blanket statements and then come back with qualifications leading to a slow erosion of credibility.

    And it's been my race bike for a couple decades. And playbike. I play pretty hard.
    #91
  12. Twin-shocker

    Twin-shocker Long timer

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    As I posted earlier if you are a playbike rider, using excessive amounts of the wrong type of 2T oil doesnt matter a great deal. But as almost all of the excess oil will find its way out of the exhaust, unless you are into lots of smoke, there is no real purpose for the added oil.

    The amount of BS linked to dyno testing is very great, and running the correct amount of the right sort of 2T oil for any particular application, will always been improved performance and less need to service clogged exhausts...............If you forget the BS, then running the right oil and mix ratio, really is a win-win situation.
    #92
  13. anotherguy

    anotherguy Long timer

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    You spew many words but say so little. So now you're a trained dynamometer operator? Care to elaborate on the "BS linked to dyno testing"?

    So let's say I've got good peak output but if I add fuel power goes down. My CO is good but hydrocarbons are high. What's the next step?

    BTW my 465 smokes little even when cold. Oil load is only part of the equation.

    So what do you ride anyway? Besides a keyboard.
    #93
  14. Twin-shocker

    Twin-shocker Long timer

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    Dyno testing is certainly very helpful when it comes to setting up serious race bikes, which are properly maintained, and owned by riders who know what they are doing.

    However for those who apparently are unable to grasp even very basic concepts related to engine set up and tuning, and ride play bikes which in most cases are poorly maintained, then dyno set up is to a large extent irrelevant.

    In this thread much has been made of dyno testing carried out by Gordon Jennings some 40 years ago.

    Today this has little relevance, other than from a historic perspective, and without exception play bike riders most of whom ride worn out old nails, would be well advised to run a lot less oil than serious competitors, which will provide cleaner pick up, increased power, and not quite so much smoke issuing from bikes being ridden at a snails pace.
    #94
  15. craydds

    craydds Long timer

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    I bought some Klotz Super TechniPlate to run in my old snail. Their directions for air-cooled 2-strokes say to run 20:1 to 32:1. I am going to try it at 32:1. Sounds a little better than the 20:1 specs in the Yamaha manual. What say the smokers?
    #95
  16. PistonPants

    PistonPants Crankcase Scavenger

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    44:1 Amsoil HP Marine for my KDX200, chainsaw and an old-ass ski-doo. None of these machines complains Happy top ends.

    Piston
    #96
  17. Scootern29

    Scootern29 Been here awhile

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    This thread is really delivering as I thought it would. :D
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  18. Twin-shocker

    Twin-shocker Long timer

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    Why use a castor based oil in a low heat engine? In terms of oil technology the castor/synthetic oils are about 5 years out of date, and a full synthetic pre-mix only oil, will do a better job in any application other than alcohol fuel burning bikes, which require a castor based oil. If you have a play bike, try using full synthetic pre-mix only oil at 60-80:1 mix (depending on application), and I think you will be very surprised at how much better it runs.
    #98
  19. anotherguy

    anotherguy Long timer

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    Have you any reference or testing to collaborate this? Not the bean oil thing because I agree. The 60-80:1 running better not to mention any longevity testing.
    #99
  20. craydds

    craydds Long timer

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    I think I was influenced by the favorable reports on the castor oils, but as you state, those reports are old. The synth/castor blend (around 80/20 ??) sounded like a good compromise, but as you state, this may be outdated. I will definitely run a full synth next go-around (will use up my synth/castor, won't toss it). This is experimentation and re-learning about 2-strokes, I've ridden 4-strokes only for the last 10 years, forgotten everything I knew about 2-strokes which was very little.