Nelson 15 RE

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    Can anyone help me to get my Nelson 15 RE to run in cold weather. When it`s warm it`s fine but in the cold it just won`t run smoothly.
    Suggestions already tried are to keep the plug leads on for a while and lag the cylinder to help it warm up. Neither have cured the problem.


    My first thought would be to raise compression a little.

    If the engine is OK with the glow leads on, and sags when you take them off (tending to sound maybe a bit rich), then reduce head clearance a little (i.e. raise compression).

    For myself I prefer to hear an engine start up sounding a touch rich, then come in to peak by itself without touching the needle.

    Head clearance SHOULD be adjusted from the warm weather to cool (I think).



    John is correct…raise the compression…
    I have three RE Nelsons and if it is cold they are very bitchy until they warm up….Doug Galbreath even suggested raise the compression if it is cold …in warm weather add the shim back..


    Yup, agree also- try to increase it by .004″ at a shot- this may require making up a shim that is thinner than the one in it- Or, you could take .004″ off the sealing surface to drop it further down into the liner. Do this until it runs consistantly or else there is a drop in rpm. If the needle gets touchy, that means it is over compressed- and, finally, if you are blowing plugs, you have gone too far too-

    The other thing that may help, if the engine is cowled, is to block off any cooling holes in the cowl. If uncowled, then a “clamp” can be made out of aluminum that surrounds the cooling fins. This acts as a heat sink and may keep heat in the cylinder- used to do this with Rossis in the olden days….


    Thanks for the advice, now I have to wait for cold weather to try it.
    We are having very unseasonal mild temperature at present.
    John Bailey

    Gilbert Morris

    I agree with earlier posts. Just want to add that if you are on the line about to make an early morning flight and the engine is acting up and you don’t already have a heat shield on, quickly rap anything around the cyl. and hold in place with a rubber band. The anything can be a piece of cardboard, piece of tissue or rag, etc.

    Gil M.

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