1978 evenrude 115 idle adjustment?

[reedskeeter]

My 1978 evenrude 115 is idled superhigh and I have no idea how to adjust it! Help!!!

 

[jakedaawg]

Did it used to be ok and then just start acting up? Or did you fiddle with something? Or did you just get the boat?

 

[emdsapmgr]

The idle on that engine is set by adjusting the idle timing. Nothing on the carb itself. Dunk the boat in the lake. Start it up and shift into forward. Set the idle rpm's 650-750. You can't set the idle when it's on the trailer in the back yard. It requires the backpressure from the water at the prop to set it correctly. Most books indicate some preliminary idle timing in degrees. Since all boats are different the idle timing is rarely what the manual says-that's just a starting point. Set the idle to the rpm's, not what degrees of timing.

 

[interalian]

Did it used to be ok and then just start acting up? Or did you fiddle with something? Or did you just get the boat?

QFT. Need more background info. And look to see if the throttle arm goes all the way back when you shift into neutral. Could be as simple as a cable adjustment.

 

[reedskeeter]

The idle on that engine is set by adjusting the idle timing. Nothing on the carb itself. Dunk the boat in the lake. Start it up and shift into forward. Set the idle rpm's 650-750. You can't set the idle when it's on the trailer in the back yard. It requires the backpressure from the water at the prop to set it correctly. Most books indicate some preliminary idle timing in degrees. Since all boats are different the idle timing is rarely what the manual says-that's just a starting point. Set the idle to the rpm's, not what degrees of timing.

What do I need to adjust once I get it into the water and in the forward position? The cable? Or a certain skrew? Or what?

 

[emdsapmgr]

The main idle screw is the large one on the spark advance lever. It pushes against the block and slightly moves the spark advance lever. As you screw it in/out you will be looking at the idle rpm on the engine's tach. I'd refer you to the original factory exploded parts diagram at: epc.brp.com. When you get into the diagram for a 78 115 hp, look for the diagram called: Cylinder and Crankcase. That picture shows the spark advance lever, as item 76 of the drawing. The idle adjustment screw is item # 75.

 

[interalian]

Idle screw is the slotted one in the arm just above the white plastic bracket. If the black plastic cap on the other end doesn't come back and touch the block when you shift back from forward, you need to adjust the throttle cable until it does.

 

[reedskeeter]

Okay thank you!