Idle adjustment

[daveydoodle]

First season for my new old 1990 Johnson 70 hp. Running good , new gas lines and carbs rebuilt by PO. Running fresh non ethanol gas and new plugs. At idle 6 -700 rpm sometimes stops including when shifting. I bumped up the idle screw 1 1/4 turns, one of two, that moves linkage on starboard side of motor. Don't really know if that was proper to do but now idles around 1000. and much better. Did the same to my little Mariner 20 few yrs. back and running good.The 70 came with VRO that I disconnected and I run 50;1 mix with a new fuel pump. Looking for reassurance on the idle adjustment. Thanks , Davey

 

[oldboat1]

The carbs probably have idle mix screws. If stalling, set them a little richer (counterclockwise).

 

[daveydoodle]

Going to try that today. Thanks much old boat.

 

[w2much]

The carbs probably have idle mix screws. If stalling, set them a little richer (counterclockwise).

Best if done in gear under load at the dock or proper test barrel

 

[Silvertip]

Too high idle speed can cause excess wear on clutch dogs/gears in lower unit.

 

[oldboat1]

A richer fuel/air mix may lower rpms, while a leaner mix can increase rpms. Object is to look for a lean setting that will allow smooth shifting and throttlling up without stalling. Use the throttle idle setting in combination with the air/fuel adjustment.