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technical question

Discussion in 'General' started by zane, Mar 10, 2000.

  1. zane

    zane Active Member

    i have a guestion for you guys. i dont want to start an argument!
    if your dealing with a TWO-STROKE bike
    is a RICH mixture to much gas or to much oil?
    remember this is dealing with a two-stroke not a 4 stroke!
    thanks
    lance
     
  2. wera122

    wera122 Guest

    Yeah, if your gas and oil are mixing in a 4-stroke you definitely have a problem. [​IMG]

    How do you get the gas pump nozzle into that little oil filler hole? [​IMG]
     
  3. Eric_77

    Eric_77 Well-Known Member

    Okay you are rich if you have too much fuel. If you run a high ratio of oil to gas you can actually lean a bike out, the gas in a given volume of oil/gas mix will have less gas and so be leaner(less fuel) So if you increase your oil mix from 40:1 to 32:1 then you will need a bigger main jet. In a test I have read about outboards (applies to all two strokes though), max power is obtained around 16:1 but plug fouling is almost instant at idle. The new electronic oil injected outboards run a variable mix of 50:1 or higher at idle and down to 20:1 at full throttle. Take this information and make your own decisions I am not an expert 2 stroke tuner. Proper jetting requires much record keeping of humidity, temp, jet size, track, etc.
     
  4. cb500

    cb500 long hair hippie freak

    hey, to rich is too much fuel in any two stroke or 4 stroke. I'[m not an expert on two strokes but most old bike run very well at 24/1 to 28/1 if you decide that you want to race a two stroke,(not recomendfor first year) I have a well sorted rd350 racebike
    that I raced last year. zane if you interrested email me.
     
  5. wyldkat1

    wyldkat1 Well-Known Member

    hmmmm...i was always told too rich was too much oil and too lean was not enough...but then again that was when i was working on sleds and not bikes [​IMG]
     
  6. wera122

    wera122 Guest

    I've heard both answers and now I'm really confused. Which is it? [​IMG]

    Actually, I thought about it for a while, and thinking in terms of a carburetor helped clear it up a little. Too much gas, rich. Too little gas, lean.

    Now somebody please tell me I'm right! [​IMG]
     
  7. cb500

    cb500 long hair hippie freak

    yes your right 122
    but like the other guy said if you increase the amount of oil you can lean it out also.
    so mixing gas and oil is an art once you get it right it the best. but if you don't get it right, well you might want to keep an extra set of piston handy.its very important to always mix the same amount. and also changing gas types can also change the ratio. two strokes is a sience. that why I don't recomend them for first year of racing [​IMG]
     
  8. wera122

    wera122 Guest

    Thanks cb500, now I can get some sleep tonight. [​IMG] I've always been a 4-stroke guy and plan on sticking with them. It makes gassing up so much easier.
     
  9. wyldkat1

    wyldkat1 Well-Known Member

    Posted by wera122:
    thinking in terms of a carburetor helped clear it up a little. Too much gas, rich. Too little gas, lean.


    Hmmm...you do have a point there...
     
  10. wera122

    wera122 Guest

    Some days I also have a point on the top of my head. It's usually a white cone shaped hat with the initials D U N C E on it. Does anybody know what that stands for?

    And why do they keep making me sit in the corner? I took a shower this morning!
     
  11. Diesel

    Diesel Well-Known Member


    I don't have a point but a big ass zipper scars my fivehead (it's bigger than a forehead, larger cranial capacity doncha know).
     
  12. wera122

    wera122 Guest

    Is the scar from where they had to take some cranial mass out because you were too intelligent and driving yourself crazy? [​IMG]
     
  13. YamahaRick

    YamahaRick Yamaha Two Stroke Czar

    Too RICH means too much fuel for the oxygen content of the intake mixture. Too LEAN means not enough fuel ... these both apply regardless of the gas/oil ratio used.

    Oil ratios are like religions ... alot of them out there, and many followers of each. Use one ratio, and stick with it. Get a Ratio Rite cup or Accu-Mix jug to have consistent ratios throughout the season. I run 24:1 in my RZ350 with lots of success. This, on a modified bike, using Amoco premium pump fuel with Yamahalube R oil. While this may affect my bike's ability to idle, it never has to idle while at the track. :)

    Regarding jetting (fuel air mixture), that is a science I'm still trying to figure out. For more good information, I'd suggest purchasing the Sudco Tuning Manual ... see www.sudco.com for more info.

    If you want to get serious about jetting, you need things like an air density gauge. If you want more info on stuff like this, join the 2 strokes mailing list.
     

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