question about oil/gas ratio

[89blaster89]

ok so im confused after reading some stuff. i always thought the more oil in the gas/oil mixture the leaner it gets. and i read a thread saying 50:1 is a leaner mixture than 32:1 , i thought that 50:1 would be richer than 32:1 since theres less oil in the mix.

 

[Herpderplol]

More of something = richer right? Thats the way it is with the oil! If you dont believe me yet, wait till someone else tells you I:I

 

[Blaner]

This is an interesting topic.

You essentially have TWO "types" of ratio with a 2-stroke.

1.) Your Air/Fuel Ratio.
---This is the ratio of parts air to one part of fuel and is determined by your jetting. If you have 1 liter of fuel with NO OIL, you have exactly 1 liter of fuel. When you add OIL to the FUEL and measure out 1 liter, you have LESS fuel than before! the 1 liter of Premix now contains say 900ml of fuel and 100ml of oil. This then means the more oil you add, the less fuel you have per unit of premix. This means the more oil you add, the leaner your premix gets in terms of fuel and air.

This means that if you run a lot of oil with your fuel (20:1) (20 parts fuel to 1 part oil) as opposed to 32:1 (32 parts fuel to one part oil) you will actually need bigger jets for the same motor to be able to supply the motor with the same volume of FUEL

2.) Oil/fuel ratio
---The amount of oil you add to the fuel determines your premix ratio. what you are doing is adding one part of oil to multiple parts of fuel. eg 32 parts fuel to 1 part oil. The more oil you add, the richer the oil/fuel ratio becomes eg 20:1. the less you add eg 40:1 the leaner your oil/fuel ratio becomes.

 

[Blaaster]

x2.

Just a small example:

If you are running 32:1 and change to 25:1, you need approximately one size main jet bigger and possibly lift the needle one clip.

 

[Herpderplol]

So we were both right..... Except I'm right on the oil/fuel (part we were fighting about ) so I still technically win...

 

[Blaner]

So we were both right..... Except I'm right on the oil/fuel (part we were fighting about ) so I still technically win...

Well you were both half right

 

[Herpderplol]

Well you were both half right

Yep. Except we were talking oil/fuel ratios... So reallllyyy I'm right and he's wrong, he never said anything about air lol... Just the oil/fuel lol

 

[Blaner]

yes, but your understanding of the matter was incomplete but anyway, well done, you win the 5m head start in the next race

 

[Herpderplol]

So... I have the oil tank still. With 28mm kikuni. An open air filter (direct on carb no box) what do you think I would be running?? It smokes a lot, and light smoke after its warmed up... I will run plot chop soon I guess

 

[Blaner]

Im not sure about the 28mm Mikuni, but on my stock 26mm Mikuni, with the mods listed in my sig, I run a 330 main and a banshee needle on middle position. thats mixing 33:1.

 

[89blaster89]

i was right about the needing to rejet though heheh

 

[Herpderplol]

We never talked about rejetting, and I knew that...