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I have a 1986 johnson 2 stroke that has just been rebuilt a year or so ago. compression is good and all cylinders firing. we go out on the lake...it will run fine for awhile and then all of a sudden it will lose rpm, doesn't shut completely off, but kicks down to about 1.5 rpm, sometimes will take off again, and sometimes will not go any faster. We have had it serviced many times..with new spark plug wires, new stator coil, new wiring and still doing the same thing. Please tell me what you think. thank you

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  • gaucli Sep 09, 2009

    it is sparking on all cylinders.

  • gaucli Sep 09, 2009

    well it seems like when it heats up it runs a little better. do you possibly think that one or both of the power packs are bad...and do you know if there is a way to check to see if they are bad?

  • gaucli Sep 09, 2009

    i hope this works...thanks

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  • Master
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Everything seems to be new in your motor. have you cleaned or serviced the air filters as well? or may be gasket is going. when the engine heats up gradually, it starts leaking. thus reducing the power and rpm. but 1.5 rpm is ridiculously low.

Posted on Sep 09, 2009

  • Vinay Tevatia
    Vinay Tevatia Sep 09, 2009

    Gaucli,
    It is very difficult to findout is the gsket is indeed gone or going. Only symptoms can indicate. Alternatively, when the motor starts going into depression, move your hand aroung the engine to see if you get the hot air blast. Dont go too close to it else you may injure yourself. have you checked up the air filters?

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  • Master
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First of all I don't claim to be an expert in 2 stroke boat engines but I will ask this much, do you mix the oil or is it injected, and have you ever thought of shutting it down & pulling spark plug to have a look at it when this occurs?

Posted on Sep 09, 2009

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