25 horse merc

[huntnfish]

Could anyone tell me which adjustment screws are which on a mid 80s 25 horse Merc? There are 2 screws on the front and another thats not a screw on the top of the carb that has a little plunger on it that gets pressed when you go to full choke. I'm having trouble with the engine idling while it's in gear. I'd like to use it to back troll and also pull cranks but it only runs for a short time then dies out. I don't want to do any adjusting until I know which screws are which. Thanks.

[huntnfish]

Anyone have any idea which screws are which on this motor? I've been messing with the screw on the right and the idle is better and it idles much better while in gear but I want to make sure I'm not going to wreck anything. Thanks

[boatfixer]

Can u post a picture?

[huntnfish]

Here is the carb. The screw I adjusted is the one on the right. The choke lever brings that black arm down that hits the top of the carb. I figured there would be some sort of butterfly valve but there isn't. I don't know how the choke works. Maybe someone could explain how the choke on this motor works also. Thanks.

[boatfixer]

The recessed screw on the right is the idle mixture screw. That should be set about 1 1/2 turns from lightly seated. From there it can be fine tuned.

There is no butterfly because its a primer. The lever pushes down on a plunger. It's tough to see in the picture, but there may also be a rod that advances the stator for fast idle.