2 stroke oil to fuel ratio

[chrismechanic]

hey guys, im my saw manual it gives 2 expamles for 1:50 and 1:33 mix.

on the fuel filler cap it says 1:40, i allways like 2 strokes to be a tad on the rich side.

so, at the moment i am mixing the fuel with the red type 2 stroke oil a tad over 1:40.

 

what ratio would be best? saw is a cs360t mcculloch.

 

thanks..

chris

[Eddy_t]

50:1 stihl or husky oil, or aspen, and remove the spark screen

 

 

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[chrismechanic]

i trust the spark screen is the mesh i can see through the silencer opening.

chris.

[geoff]

Eddy is right, adding more oil to the mix actually makes the saw run leaner, because the fuel to air ratio is changed, ie, less fuel, as it is replaced with more oil (which is not combusted).

 

Sounds a£$e about face, but it is the truth!

[chrismechanic]

Eddy is right, adding more oil to the mix actually makes the saw run leaner, because the fuel to air ratio is changed, ie, less fuel, as it is replaced with more oil (which is not combusted).

 

Sounds a£ about face, but it is the truth!

 

ok so.. i only mix up 500ml of fuel at a time, so am i correct to add 10ml of 2 stroke oil to get a 1:50 mix?

thanks,

chris

[Eddy_t]

i trust the spark screen is the mesh i can see through the silencer opening.

chris.

 

Yes, and running richer on either of those oils just craps your engine up, and as less petrol is in the mix, you loose power, it doesn't lean the mix as in an engine lean seize, as in you have too little combustibles to actually run the engine

 

 

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[geoff]

That sounds right Chris, as long as you are using a good quality oil that specifies 50/1.

 

Mind you, my maths ability got me in all sorts of trouble over the years!

[wyk]

Run your saw very rich, regardless of mixture, on a nice cold day and watch all the blue smoke that comes out of it - some of that oil does make it to the combustion chamber.

[chrismechanic]

thanks wyk and geoff.... i just removed the spark arrestor and it has started to get clogged allready.. looky..

 

 

 

out of focus but you can see the carbon, i have only used this saw a handful of times. i rarely run it long enough to use a full tank.

which is only 400ml on this saw

great advice guys

thanks.

chris

[geoff]

Run your saw very rich, regardless of mixture, on a nice cold day and watch all the blue smoke that comes out of it - some of that oil does make it to the combustion chamber.

 

Yep, all the oil makes it to the combustion chamber, & out through the exhaust, but it does not contribute to the combustion process, so less fuel & more oil in your mix actually results in a fuel deficiency in the air/ fuel ratio.

Now you got my head in a spin, but it is correct.