Nissan 8hp tuned up to 9.8?

Discussion in 'Outboards' started by DennisRB, Jan 17, 2012.

  1. DennisRB
    Joined: Sep 2004
    Posts: 1,268
    Likes: 25, Points: 48, Legacy Rep: 228
    Location: Brisbane

    DennisRB Senior Member

    Is the Nissan 8hp just the same motor as the Tohatsu 8 and 9.8?

    If so does this mean it is a tuned down 9.8? Respectively does that mean it can easily be tuned up to 9.8? What would be needed?
     
  2. Chuck Losness
    Joined: Apr 2008
    Posts: 311
    Likes: 37, Points: 28, Legacy Rep: 135
    Location: Central CA

    Chuck Losness Senior Member

    If you are asking about a 4 stroke, I can't help you.
    I have a Nissan 8hp 2 stroke. The Nissan 8hp 2 stroke is made by Tohatsu and is the same as the Tohatsu 8hp . The 9.8hp is the same basic engine with 3 changes as I recall. The jetting in the carb is different, the cylinder head is different and the exhaust plate on the side of the engine is different. I have not made any changes to my engine. A friend of mine changed the jets in the carb in his 8hp to the 9.8 jets and thought the change made a difference. He is now able to get up on plane in his dinghy faster and easier than before the change.
     
  3. DennisRB
    Joined: Sep 2004
    Posts: 1,268
    Likes: 25, Points: 48, Legacy Rep: 228
    Location: Brisbane

    DennisRB Senior Member

    Thanks its the 2 stroke. I have been searching and some sites say all you need to do is change the carb as it is bigger (jets alone will only adjust the mixture and not allow more airflow). I did not know the head and exhaust plate is different.
     
  4. Karhu
    Joined: Jun 2018
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    Location: Gumbostrand

    Karhu New Member

    The difference is in compression and on the exhaust cover. Some rejetting may be needed.
     

  5. powerabout
    Joined: Nov 2007
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    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    You always need to look in the parts book of the 2 engines, its the only way to know
     
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