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    Charles Baum
    Re: Correct fuel:2 cycle oil mix. My 142 manual says 40:1...escalated
    General Product Question posted August 2, 2012 by Charles Baum 
    2378 Views, 3 Comments
    Question:
    Re: Correct fuel:2 cycle oil mix. My 142 manual says 40:1 (3.2 oz. per gallon) but the Husqvarna 2 cycle oil bottles are 50:1 (2.6 oz. per gallon). Isn't that 40:1 wrong?
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    Answer

     

    • Karla

      Charles,

      If your manual says 40:1, I am sure its probably correct. I would definitely use the 40:1 mix, since your only .6 oz per gallon more than the 50:1 mix, and a little more oil is better than a little less oil. I have had many 2 stroke engines with all kinds of mix ratio numbers (16:1, 25:1, 32:1. 40:1. 50:1) , even an old Homelite 330 that suggests 16:1 mix or 8 oz of oil to 1 gallon gasoline, and yes I run my Homelite at 16;1. and its 30 years old and still running.

      If in doubt, Don't skimp on the oil! I hope this helps.

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      • Charles Baum

        Thank you so much Karl. I think you answer makes a lot of sense - when in doubt, refer to the manual. Thanks.

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      • George McCoy

        Hi Karl and Charles

        Careful with adding more oil to the premix thinking it may help lubricate better.  The premix will become more viscous (thicker) and will not flow through the fixed size super small jet orifices in the carburator as easily and the saw may run very lean and sieze.   The real enemy is correct air-fuel ratio with saws as a lean mix will sieze a saw in minutes due to piston expansion (unradiated and scavenged heat).

        Imagine a ratio of 1:1 super think mixture and how it might struggle to flow through a small hole just a few thousanths of an inch diamter (jet).  Now imagine a ratio of 100:1 and how thin it is and easy to flow like water.  Hence, a higher ratio of 50:1 will flow more 'fluid' and carry more oil into the combustion process than a 40:1.  i.e. a 50:1 will run rich and a 40:1 will run lean given the same metering needle position and fixed jet size.

        The above is based on years of racing 2 stroke motorcycles with very high RPM engines, including Husqvarna, back in the 60's and 70's !

        I've used a synthetic racing oil BelRay MC1 for high RPM racing engines in all my saws at 50:1 for the past 30 years.  I just put a ring on my 359 after more than 125 cords of wood and I didn't need the new ring, piston still looked new except slight carbon on top and cylinder still had original 140* inclusive angle cross hatch hone marks from the factory back in 2004.  I opened it up just for fun, not to solve a problem since it just keeps running stronger than my pal's MS 440 Stihl and I wanted to learn why.

        Cheers

        George

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