1997 Force 120 Idle Will Not Settle Down

[JDusza]

1997 Force 120 ELPT, 4 cylinder, 2 stroke, serial 0E277049.
When coming off high speed and throttle lever is pulled to neutral, the engine drops revs normally but reaches a point where it will not come down to a quiet, shifting idle speed.
Linkages all respond, throttle cam is in correct position, however, the throttle cam follower of the carburetor does not contact the cam when in neutral. Strange but true.
Seems the advance would be responding okay since it is based on hard fixed mechanicals.
Any idea what's keeping the speed up?
Thanks,
J

 

[pnwboat]

Are the throttle plates in the carbs pretty much closed? Can you move the cam with your fingers to close the throttle plates more? The throttle plates should open and close in sync.

If the cam is not touching the roller in neutral, I would think that there is something hanging up the linkage, or the linkage is out of adjustment.

The roller is on an eccentric shaft and is held in place with a lock nut. If you loosen the lock nut and turn the shaft, it will move the roller either closer or farther away from the cam.

There is an adjustment on the linkage that connects both carbs to get them opening and closing in sync, but not sure that would keep the throttle plates from closing all the way. Maybe the linkage to the bottom carb is out of whack and keeping it open more than it should be?

 

[JDusza]

Thank you. There is a good chance that a throttle butterfly is open more than it should be. I'll have a look.
J

 

[JDusza]

Got back to the boat.
Visually it didn't look like the butterflies were open but when I released the carburetor linkage the bottom throttle relaxed to full close and the throttle cam follower went right home making contact with the cam. Perfect!
Revs settled right down and cam follower position makes sense.
I'll bet I originally tuned it to an ailing fuel delivery system and after running what is now several tanks of clean fuel, the system had cleaned up and gone "out of tune".
Thank you.
J