Just Installed Your Clean Carb? It Needs a Tune
Even a perfectly ultrasonically cleaned carburettor isn't just "plug and play." We set the float height and baseline the screws on the bench, but the final air/fuel mixture and idle speed must be dialled in for your specific engine.
Always tune your outboard in the water or a test barrel. Tuning on flush muffs won't give the exhaust the proper backpressure, and your settings will be wrong when you actually launch the boat.
How to dial in your idle mixture:
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Warm it up: Start the motor and let it reach normal operating temperature. Never try to tune a cold engine.
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Find the sweet spot: Locate the idle mixture screw. Slowly turn it in (clockwise) until the engine starts to stumble and sound lean. Then, slowly back it out (counter-clockwise) until it starts to bog down and sound rich.
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Lock it in: Turn the screw to the exact halfway point between those two stumbling points. That is your smoothest idle.
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Set the idle speed: Once the mixture is right, adjust your main idle speed screw so the engine sits at the correct RPM (check your manual, usually around 700-800 RPM in forward gear).