25 Merc Idle RPM??

[J Walters]

I am looking for some info on what my 1986 25 merc 2 stroke should idle at. I had to change the throttle cam and I am also trying to get it running and little smoother at idle. I know that i will need to adjust the idle air mixture but I need to know how low it should idle. It is idling at about 1600 rpm right now. I have a feeling that is way too high. There is nothing in my service manual about it. I am checking it with a MAC TOOLS timing light that can check 2 stroke RPM as well as 4 stroke and timing. Thanks, Jeremy

 

[lots of boats]

Re: 25 Merc Idle RPM??

Hi
I am trying to remember how these things worked but I think if you changed that stepped arm on the side, and that is the throttle cam, the one the roller goes along and lifts, then before adjusting the carb you have to make sure the roller goes all the way back. Does that make sense?

 

[8075mercury]

Re: 25 Merc Idle RPM??

Agree with the above.

Idle should be 700 to 800 rpm in forward gear.

The hex nut on the throttle cam is used to adjust the throttle cam. I think you have a elongated hole in the throttle cam. The straight line on the throttle cam should align with the roller.

Hope this helps.

 

[Riverman128]

Re: 25 Merc Idle RPM??

I just did this on a 1985. You may want to look at the idle screw adjustment. I would back the screw all the way out. Then align the marks on the throttle cam. You may need to adjust the idle screw in (increasing idle speed) to obtain the 700-800 RPM in gear with engine warm. Your manual should show you where the idle screw is located (starboard side, near underside of flywheel, and slightly to the rear).