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  1. #1

    Default NS5B Sometimes Won't Give Full Power

    Yesterday I operated my Nissan 2-stroke, 5 horsepower (NS5B) for about an hour, and for most of the time it ran as well as, maybe even better than, any time in the past 8 years.

    A few times yesterday, however, when I would bring the motor to full throttle, the power would be about 1/2 of what the engine is capable of. The sound and speed were noticeably different. Then, after anywhere from maybe 100 to 500 yards of travel, it would return to full output.

    I've considered the possibility this is because the boat (which is heavy for a 5 horsepower) was taking a long time to get up on plane, but I'm reasonably confident that is not the case, especially because sometimes in the past this situation would occur the whole time the boat was underway.

    Last week I went through a fair amount of maintenance tasks on this motor (changed lower unit oil, removed old gas from tank, and replaced it with fresh gas and oil, replaced kill switch, inspected and lubed prop shaft, changed fuel filter, and sparkplug, and added some Sea Foam to the fuel in case there might be some carbon buildup in the carburetor).

    Any ideas on the cause or a solution? Thanks for any input

  2. #2

    Default Re: NS5B Sometimes Won't Give Full Power

    It sounds like there is a lack of fuel at wide-open-throttle.
    Probably due to a plugged main jet in the carburetor.
    You can carefully take the carburetor apart and clean it.
    Any particles or varnish in the float bowl should be removed as they
    might plug the jet. Just note carefully how it came apart and
    don't lose any parts.

  3. #3
    Join Date
    Mar 2010
    Location
    Buffalo, NY, USA
    Posts
    2,080

    Default Re: NS5B Sometimes Won't Give Full Power

    Usually a fuel issue. Seafoam may not be your friend here. It's mostly mineral spirits. If you need to de-carbon, use the OMC spray product.
    Paul
    Buffalo NY USA

  4. #4
    Join Date
    Aug 2017
    Location
    South Africa
    Posts
    108

    Default Re: NS5B Sometimes Won't Give Full Power

    High speed jet, soak in carb cleaner and blow with compressed air, use thin guitar string to make sure holes are unclogged ....

  5. #5

    Default Re: NS5B Sometimes Won't Give Full Power

    Thanks for the suggestions. I'll have to look for the OMC product again. West Marine did not carry it. If it's still clogged then I will try to do the carb clean

  6. #6
    Join Date
    Mar 2010
    Location
    Buffalo, NY, USA
    Posts
    2,080

    Default Re: NS5B Sometimes Won't Give Full Power

    Quote Originally Posted by deejaycee_2000 View Post
    High speed jet, soak in carb cleaner and blow with compressed air, use thin guitar string to make sure holes are unclogged ....
    If wanting to clean the carb, Use carb dip for 4 hours, then blow-out liberally with generic spray carb cleaner. NEVER push any kind of wire into any passage in any carb.
    Paul
    Buffalo NY USA

  7. #7

    Default Re: NS5B Sometimes Won't Give Full Power

    thanks for the clarification re wire

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