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Engine Idle Speed Adjustment(Boat-In-The-Water) Mercury I/O

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DO NOT leave helm unattended while performing idle speed adjustment. Boat MUST BE moving forward (not tied to the dock) when setting idle speed.

Engine should idle at 650-700 RPM with boat in the water, drive unit in forward gear and engine at normal operating temperature. If idle speed is incorrect, proceed as follows:

1. Disconnect throttle cable from carburetor. Be careful not to lose spacer on anchor stud and spacer and bushing on throttle lever screw.

2. Start engine and place remote control lever(s) in forward gear, idle position. Adjust idle speed adjustment screw to obtain recommended RPM.


Throttle cable brass barrel MUST BE adjusted properly (in next step). Over-adjusting barrel in the other direction will exert excessive pressure on throttle lever, which could cause damage to carburetor linkages.

3. Stop engine. Readjust cable brass barrel (to compensate for throttle lever movement) and reinstall throttle cable. Be sure to tighten attaching nuts.

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