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  1. #1
    Petty Officer 2nd Class
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    Jul 2011
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    wisconsin
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    Default idle adjustment on 75' 70 hp johnson

    Hey guys I was wondering how to get more rpm at idle my engine takes forever to get started and have to feather my controls between choke and start . The screw on the timer base is screwed all the way in and the roller is touching the area where it says start on my carb linkages I have a PDF manual I downloaded but its not very clear also how can I check for wot? Remove throttle cable and move timer base to see how far it goes then install my cable to that point.? Motor is new to me this year been a battle but it runs good when it starts carbs have been gone through along with lines filter plugs new tank

  2. #2
    Master Chief Petty Officer
    Join Date
    Jul 2008
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    813

    Default Re: idle adjustment on 75' 70 hp johnson

    Let's start with the basics...

    Are you using the warm up lever on the control box? That raises idle speed significantly.

    If yes, remove the carbs cover(aka, air silencer). The links must be adjusted so that chokes ALL close COMPLETELY when choke is applied.

  3. #3
    Master Chief Petty Officer
    Join Date
    Jul 2008
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    813

    Default Re: idle adjustment on 75' 70 hp johnson

    Here's the Factory service manual for your specific 1975 70HP Johnson. Only paint codes are different between Evinrude and Johnson 1975 70hp manuals. The pic shows a Johnson manual, although the listing says Evinrude.

    $29.99 delivered

    As you've found out, the aftermarket manuals are marginal and often contain errors.

    http://cgi.ebay.com/ebaymotors/1975-...item56430febce

    Edit: Just verify the correct model year/age of your motor, it should be model #70ESL75. Starting with 70(which is HP) and ending with 75(which is 1975).

  4. #4
    Petty Officer 2nd Class
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    Jul 2011
    Location
    wisconsin
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    115

    Default Re: idle adjustment on 75' 70 hp johnson

    Yes using the warmup lever on the control box to get it to run been shifting into neutral then lifting warm up lever to keep it idleing its gotten annoying and needs to be fixed. I have replaced coils fuel pump every fuel line possible new squeeze ball also added a tell tale changedy impeller rebuilt carbs they are all synced and linked new plugs the idle screen on the timing lever is turned all the way in idles about 550. Rpms then dies needs to be turned up some seems like when I do spin the motor over and get it running it smokes until the cylinders are cleared out kind of embarrassing . Fixed everything.without manual so far just read on the.forums here and taking it apart even ran seafoam through it didn't decarbon it yet tho that's Fridays project

  5. #5

    Default Re: idle adjustment on 75' 70 hp johnson

    Check the timing...on the muffs should idle around 1000 to 1100 rpm...or 750 oor so in water...at WOT make sure butterflys are wide open...the lync and sync from manual should get you fairly close...you should be able to lengthen rod to cam and slighlty adjust idle rpm!!

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