Idle mixtures can take a while to get dialed in just right. Engine must be IN the water and IN Forward gear. Tied off to the dock works well. First you want to adjust each carb to "Best Idle'. This can take some time as you must give the motor time to respond to any change. Especially if turning the mixture screw IN to reduce fueling, you have to give the motor time to burn off any excess fuel. Not just from the carbs but any fuel accumulated in the recirc system as that is being pumped back up into the intake of another cyl. You have to be certain all excess fuel has been spent and only what is being passed by the carbs.
The more time spent perfecting this 'Best Idle' the better the motor will run later.
'Best Idle' is not rich enough to allow the motor to accelerate on rapid throttle opening. All carb idle mixture screws must be set even richer to allow crisp clean immediate acceleration. Often this is almost 1/4 turn farther out from 'Best Idle', but too much will load up spark plugs, can cause a bog and excessive fuel consumption. Start at almost 1/8 turn farther out than your 'Best Idle'. Test this by slamming the throttle wide open as in doing a hole shot acceleration. ANY hesitation, bog, or lean cough then open each just the width of the screwdriver bladeslot, repeat the acceleration/throttle test. Repeat adjustment and testing to perfection.
NOTE: A heavier loaded boat, more fuel, coolers, people, equals more load and the motor will need even slightly more fuel to accelerate. Adjust to one bladeslot more than perfection to allow for this.
