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Compression for 3hp Evinrude Lightwin

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  • Compression for 3hp Evinrude Lightwin

    I have a 1962 3 hp Evinrude Lightwin that was given to me, that I have not been able to get going. Coils and points are all new from past owner, have checked and set to manual specs. done a compresion check and to me is uneven on both cyclinders readings from 10 to 55lbs max on bottom cyclinder and 40-45 lbs on top cyclinder. Can not find anyware what compression this motor is suppose to have anybody know? Also if you remove the top plug I noticed while checking spark the motor starts on very first pull? will not do this with the bottom plug out and top plug in. Mixing gas ratio at 24:1 is this correct? Any help with these things is welcome, debateing weather worth moving forward with this motor as far as repalceing rings, rebuilding motor head and sinking more money into it or just make a boat achor out of it.

  • #2
    Re: Compression for 3hp Evinrude Lightwin

    Howdy, BB.

    Welcome to iboats.

    Actually, it sounds to me like you need to refine your technique on the compression test.

    There is no spec on psi, but that engine would normally give 50psi or better on a correct test. The numbers you quote are not really useful.

    Check out the compression test procedure in the Top Secret File ^^^ and give her another shot.

    That is the best small outboard ever made, by anyone, and is worth saving. I would definitely find and fix her ailment(s).


    • #3
      Re: Compression for 3hp Evinrude Lightwin

      So the engine tries to run on the bottom plug only? How are you checking spark, you should use an air gap tester, the spark should jump a 3/8" gap and be bright blue. It sounds like the top plug is not firing properly.


      • #4
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        Re: Compression for 3hp Evinrude Lightwin

        Thanks guy's for the info. striped the motor down today and 3 out of 4 of the rings was stuck. So now it's just a matter of locateing the parts to put things back togather. I have been told Napa can fix me up with everything I need for this 62 lightwin? The check for fire in the spark plug was done by removing the top plug and laying over against the case of the motor to see what type of spark it is throwing. So on the compression anything over 50 lbs. for this motor is considered good? A small engine guy told me he would think it would be up around 100 lbs. of compression? Thanks again any addtional info would be a big help.