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  1. #1

    Default 1956 Johnson Seahorse 15hp

    Hello I have a 1956 Johnson Seahorse 15hp that I have finally gotten to run. The issue I have is although I have used the TWC 3 at a 25:1 ratio the motor seems to be smoking way too much. It even has oil dripping from the lower cowling. I can get the motor to contiguously run (a bit rough) at an rpm above idle but as soon as I turn throttle to an idle the motor stalls. I have installed new plugs Champion J6C and wires,coils and removed and cleaned the carb. I have preset the high and low speed adjustments at 1 1/2 turns out but this issue continues to remain. I am running the motor in a water barrel and there seems to be a good bit of oil in the barrel water as well. Any help with this issue would be greatly appreciated I am so close to having this motor water ready but yet so far away

  2. #2
    Join Date
    Feb 2001
    Location
    Central West Florida
    Posts
    15,775

    Default Re: 1956 Johnson Seahorse 15hp

    The problem is that the adjustable slow & high needle valves at 1-1/2 turn out are at the initial setting whereas they need to be adjusted properly from that point.... as follows:
    ********************
    (Carburetor Adjustments - Two Adjustable N/Vs)
    (J. Reeves)

    Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

    Setting the high and low needle valves properly:

    NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.

    (High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

    (Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

    When you have finished the above adjustments, you will have no reason `to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
    ********************
    We occasionally have questions. If you fail to answer, it may affect ours.

  3. #3

    Default Re: 1956 Johnson Seahorse 15hp

    Thank you Joe I will attempt your directions and let you know how it works out this was my dads motor and would like to put it back in use on his old boat as well

  4. #4
    Join Date
    Nov 2011
    Posts
    2,487

    Default Re: 1956 Johnson Seahorse 15hp

    1. Smoke is normal
    2. Oil in the barrel is normal
    3. One and a half turns on the high speed is way, way, way too much. 3/4 turn prpbably will need to be leaned out in final adjutment.
    4. Get it out of that barrel and onto a boat on the lake, then get it properly adjusted and you will find it is a whole different motor.

  5. #5

    Default Re: 1956 Johnson Seahorse 15hp

    Quote Originally Posted by fdrgator View Post
    1. Smoke is normal
    2. Oil in the barrel is normal
    3. One and a half turns on the high speed is way, way, way too much. 3/4 turn prpbably will need to be leaned out in final adjutment.
    4. Get it out of that barrel and onto a boat on the lake, then get it properly adjusted and you will find it is a whole different motor.


    Thank you I will try the new position for the high speed and then put on boat hopefully for a final adjustment. Do you think that the change in the high speed adjustment will correct the idle issue

  6. #6

    Default Re: 1956 Johnson Seahorse 15hp

    Thank you I will try the new position for the high speed and then put on boat hopefully for a final adjustment. Do you think that the change in the high speed adjustment will correct the idle issue

  7. #7
    Join Date
    Sep 2010
    Posts
    17,554

    Default Re: 1956 Johnson Seahorse 15hp

    You also need to adjust the low speed needle to compensate for fuel and local atmospheric conditions.-----The factory / book settings are only to get the motor to start and keep running.

  8. #8

    Default Re: 1956 Johnson Seahorse 15hp

    Should I start with the 1 1/2 turns on the low speed or is that too much as well?

  9. #9
    Join Date
    Feb 2001
    Location
    Central West Florida
    Posts
    15,775

    Default Re: 1956 Johnson Seahorse 15hp

    Quote Originally Posted by hal5778 View Post
    Should I start with the 1 1/2 turns on the low speed or is that too much as well?
    Just follow my instructions to the letter and you'll do just fine.
    We occasionally have questions. If you fail to answer, it may affect ours.

  10. #10

    Default Re: 1956 Johnson Seahorse 15hp

    Thanks Joe and all who responded I will let you know how things work out. On a different note I also have a 1957 10hp Johnson I will be working on after the 15 is complete and I am looking for at this point a throttle lever selection band (tiller has a white handle) and also I need what appears to be a nylon keyway which is located at the bottom of the vertical arm going from the tiller handle gears to the pivot arm on the top if anyone knows where I can obtain these please let me know. Thanks

  11. #11
    Join Date
    Nov 2011
    Posts
    2,487

    Default Re: 1956 Johnson Seahorse 15hp

    The nylon pin is part number 304155. The throttle band was sold under a bunch of numbers, only difference in color, etc. Two numbers were 203260 and 303110. May be available here at iboats from their OEM parts source.

    OR go to Antique Outboard Club's website a post a want ad. Those parts are a likely find in lots of goody boxes

  12. #12

    Default Re: 1956 Johnson Seahorse 15hp

    Thanks again

  13. #13
    Join Date
    Jun 2013
    Location
    Duluth Mn
    Posts
    2,022

    Default Re: 1956 Johnson Seahorse 15hp

    Try Tim's outboard in Hackensack Minnesota at 218-682-2331. Also try opening cowling to supply fresh air whenever tuning in a barrel. Even use an electric fan to introduce fresh air
    Or......do it out on the lake.....in the open air.

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