1974 70 hp Johnson

Discussion in 'Boat Tips' started by Skunk Master, May 29, 2006.

  1. Skunk Master

    Skunk Master New Member

    Messages:
    3,366
    State:
    Colinsville, Il
    I think I need to adjust the carbs, need info on how to do it.. Cold Natured, Runs good full throttle, but wife starts getting nervous.. Half throttle not bad... 1/4 throttle can hear it struggling... Idle, not very long before it starts missing and dies... Fast idle sounds rough too... If you try putting it in gear slowly and easing it around launch area it dies.. ( very embarrasing ).. I've worked on everything but boat motors, been a mechanic most of my life, so I'm pretty sure I can adjust with a little help..
     
  2. Arkie55

    Arkie55 New Member

    Messages:
    669
    State:
    Mississippi
    Hickshh,
    Sounds like a carb problem. I suspect it is pretty gummed up or trahsey. Most outboard carbs are easy to work on. I have a 35hp Evinrude and a 60hp Johnson. Carbs are almost exactly alike expect for size. I suggest you remove the carbs and give them a good cleaning. When adjusting the carbs, screw the adjustment screws in all the way until they seat. Then back them off 1 1/4 turns and start from there. When setting the low speed (idle) make sure you have it in the water. You can get close with motor running on the muffs but final adjustments need to made on the water. If you'll check the post here, I think BobPaul has a section on carb cleaning and adjustments.
     

  3. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    Harold go get you some sea foam and do a good decarb and see if that will help. After the decarb change the plugs and put you some QL77JC4 champion plugs in and gap them at 35 or 40.

    If that doesn't solve the problem then tear the carbs down and soak them and install new kits.
     
  4. Skunk Master

    Skunk Master New Member

    Messages:
    3,366
    State:
    Colinsville, Il
    Thanks for the reply guys, I really appreciate it.. I'll keep you posted on the outcome...
     
  5. Bobpaul

    Bobpaul New Member

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    3,039
    State:
    Supply NC