idle mixture screws...

[mapleleaf]

After 2 seasons with a poor idle, I've found ( cuz i'm dumb) that by toying with my idle mixture screws my boat idles much better. Since I don't know anything about this what would some of the hold backs be to me simply turning on them until the boat runs well?
We never water tested the carb after its rebuild and I had just settled for a fast idle, I've got it down betweeen 6-700 now and am so happy. It does however almost die when I rev the throttle, but then hops back up to 600 rpm.....Any guide lines I should be following when adjusting those screws???

[CornRickey]

Sounds like the accelerator pump is bad.

[Ptownkid]

There's a bunch of vids on youtube John. Just search idle mixture screw adjustment. You need a simple vacuum gauge, princess auto sells them cheap. Good luck!

[cadunkle]

Turn screws all the way in, lightly seat (do not tighten or you will damage the screw and/or metering block). Set each out 2.5 turns. Start engine at operating temp and if idle is rough, turn both out .5 turns at a time until idle is smooth. Adjust throttle stop screw for desired idle RPM (around 750 in neutral should be good). Turn idle mixture screw in slowly, 1/8 to 1/4 turn at a time until engine stumbles (RPM drops), turn screw out 1/4 turn. Repeat for other idle mixture screw. Now check your RPM and adjust the throttle stop screw if RPM has changed from your initial setting. Re-adjust the idle mixture screws again, after each time you change throttle stop screw position. Basically you are adjusting for highest idle RPM/highest vacuum at the throttle stop setting that gives you the desired idle RPM.