Outboard running rough and I need help

[Mhorton1911]

So it’s a Nissan 140a 2 stroke with 4 carbs. The motor idles fine, but when given gas it starts to make noise (surge?) and shake bad. I have throughly cleaned the carbs twice and have tried my best to sync the carbs, but I’m not sure they’re 100% synced. New gas tank, about half of the fuel lines are new, the rest have been blown out. Anyone have any ideas? I’m at a loss and am getting frustrated.

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[Sea Rider]

Welcome to Iboats,

Is the carb's rod well synched to the timing advance ? If that motor has individual small ignition coils, troubleshoo each with a spark tester to go from there. Probably more than one are not firing or firing poorly ?

Happy Boating​

 

[Mhorton1911]

Best I can figure the rod to the timing advance is, I tried adjusting it and it didn’t get any better. Al for the coils, all of the spark plugs have spark.

 

[pvanv]

What method did you use to clean the carbs? If you didn't completely disassemble, soak overnight in real carb dip and then blow out with generic spray, you likely need to do that.

 

[Faztbullet]

That is called "4 stroking" and need to rev up with advance arm so timing advances with fuel delivery.