Re: Adjust Idle
yes, you want as close to 600rpm or as low as possible for idle on a merc outdrive so it doesn't bang when you put it in gear. the tradeoff of increasing idle more than 800rpm so the motor idles better is you're putting more wear and tear on the drive when you shift it into gear. 700rpm I think is acceptable, but at whatever rpm you shift at if it bangs into gear then it's a good idea to lower the idle as close to 600 as possible.<br /><br />To adjust the idle, the place to start is the idle set screw on the throttle linkage on the carb. turn clockwise (inward) to raise idle. There is an idle mixture screw also, and may great improve the idle by riching or leaning out the idle mixture. With carb'd motors the outside temp can have a big affect on idle quality. You should only need to turn this screw 1/4 turn either way for routine adjustments.<br /><br />The general procedure for setting the idle mixture on most carburetors is, once motor has reached operating temp and idle is set at the desired rpm (go for 650 if in neutral), turn idle mix screw inward (clockwise) to lean out mix till idle isn't smooth anymore or starts to drop. Remember this setting. Then back screw out to richen mix (idle rpm will rise) until gets rough again and starts to drop. Remember this setting. Now turn screw back in halfway between those two points where the idle dropped on you. It's best to do this adjustment with boat in the water in gear, but in the water in neutral is just as good. If you do it on land, the idle mix will be off when you put the boat in the water due to backpressure on the exhaust with the sterndrive. <br /><br />And also know there are many factors that contribute to a smooth idle in addition to the idle mixture setting: the carburetor in general, ignition system, valvetrain, and coolant temp. But you said everything else was running nice, and also to keep it simple english so all you should need to do is adjust the idle set screw and only tweak the mixture screw.
