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  1. #1
    Join Date
    Feb 2013
    Location
    South Jersey
    Posts
    5

    Default Ignition timing issues

    Hi, I have a 1988 Nissan NS90A Same as Tohatsu M90A. The engine has been sitting for 3 years. I rebuilt the carbs with oem rebuild kits. I completely cleaned every port and passage. I did the link and sync as per the factory manual. In the manual, it says that any engine coming out of long term storage should use a tank of gas at 50:1. I cleaned the oil reservoir, put all new oil lines on and purged the oil pump. I am using Yamalube 2M 2 stroke oil. When I started the engine, it has a lean sneeze. will pop, and a puff of smoke comes out, then catches up to itself. I noticed fuel pouring out of the bottom carb. I took it apart to find the brand new float was full of gas. I thought I found my problem. I put one of the old floats back in after fully cleaning the carb again. I did the same to the other 2 carbs. Floats were fine but I took everything apart and cleaned them again. Reinstalled. Did a link and sync again. Same results. I get a lean sneeze. I checked the plugs, they are fine. They are brand new. Calls for b8hs10. I have br8hs10 in there.&nbsp;&nbsp;<br>&nbsp;The manual calls for 5 degrees after top dead center. If I hold the plate to 5 degrees BEFORE tdc, the engine runs great with no sneeze. I am really confused trying to figure out why it sneezes. Will double oil cause this? Using a resistor spark plug? After going over the manual again, it says to use 89 octane fuel. I didn't realize this and am running 87 right now. I don't think that would cause it, but maybe I am wrong. I want to put the boat in the water and go for a ride, but I don't want to burn a piston or do any damage. Any help or suggestions would be great. Maybe this engine just runs that way? Thanks to all for reading. By the way, the engine runs great at higher rpms. Just not at idle.&nbsp; Compression is at 120 for each cylinder also.

  2. #2
    Join Date
    Sep 2010
    Posts
    22,826

    Default Re: Ignition timing issues

    If carburetors have low speed mixture screws then open them 1/8th turn at a time.----Perhaps the sneeze will go away.-----Timing on outboards is fixed and normally needs no fiddling.

  3. #3
    Join Date
    Mar 2010
    Location
    Hamburg, NY, USA
    Posts
    3,335

    Default Re: Ignition timing issues

    87 octane is OK. Resistor plugs are fine. Idle timing isn't that critical. As racerone suggested, perhaps go through verifying idle mixtures.
    Paul
    Certified Tohatsu TLDI Technician
    Hamburg, NY USA

  4. #4
    Join Date
    Feb 2013
    Location
    South Jersey
    Posts
    5

    Default Re: Ignition timing issues

    Racerone, setting the timing per the the manual is easy. A couple of measurements of the rods and adjust the stops. Manual says 1 + or - turn from seat. I tried setting them all to 1 turn out and turn increments OUT but not in. What is the best way to set these screws? Seat them all, and back out ⅛ at a time? Paul, you mention that idle timing isn't that critical. Would a sneeze be acceptable at idle then? Can I safely put this thing in the water as long as there are no lean pops at higher rpms? Thanks guys

  5. #5
    Join Date
    Mar 2010
    Location
    Hamburg, NY, USA
    Posts
    3,335

    Default Re: Ignition timing issues

    I usually start with pilot screw at about 2 turns out.
    Paul
    Certified Tohatsu TLDI Technician
    Hamburg, NY USA

  6. #6
    Join Date
    Sep 2010
    Posts
    22,826

    Default Re: Ignition timing issues

    Lean sneezing / miss at idle has nothing to do with timing.------Lean sneeze is much miss-understood.----So I would concentrate on carburetor / low speed mixture issues.

  7. #7
    Join Date
    Feb 2013
    Location
    South Jersey
    Posts
    5

    Default Re: Ignition timing issues

    Quote Originally Posted by racerone View Post
    Lean sneezing / miss at idle has nothing to do with timing.------Lean sneeze is much miss-understood.----So I would concentrate on carburetor / low speed mixture issues.
    Do you start adjusting from the seated position? Does turning them in or out lean or enrich the mix? Thanks for your reply

  8. #8
    Join Date
    Mar 2010
    Location
    Hamburg, NY, USA
    Posts
    3,335

    Default Re: Ignition timing issues

    Quote Originally Posted by goodforbrains View Post
    Do you start adjusting from the seated position? Does turning them in or out lean or enrich the mix? Thanks for your reply
    Clearly you are not familiar with carburetors. Start lightly seated, then open counterclockwise to about 2 turns. Further adjustment is done on the boat in the water. Adjust idle stop to specified rpm, then readjust mixture for highest speed, then readjust idle stop. Once satisfied, richen about 1/4 turn for stability.
    Paul
    Certified Tohatsu TLDI Technician
    Hamburg, NY USA

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