Low Idle?

[rboat]

I have an older 88hp evinrude, plain jane 2 cycle pre-mix carbed engine. The only thing I did was install new spark plugs. Now it seems to idle to slow and sometimes stalls. I turned the idle screw in about a quarter turn when I returned home. I have not tested it again, but wondered if anyone knows how much adjustment would be close to correct. I really don't want to adjust while its running with the fly wheel close to the adjustment screw. Any help? Thanks.

[tntitans21399]

Check your spark plug wires and ignition coils. I just had the same thing. It would start and idle if I gave it gas but going to gear it woukd die. I saw a ignition coil that connects to the spark pkug wire had broken off and another cylinder wire came lose so it was running on 2 out of 4 which wasn't enough.

[Way2slow]

Not sure what you call the idle screw but it sounds like you most likely turned turned the wrong thing. When the motor has been properly adjust so all the Link and sink points are properly aligned, the idle speed is adjusted by the timing rod going to the timer base. If you adjust it by any other screws on the linkage it throws the sink points.

As for the low idle itself, was the motor running smooth and making RPM?

One thing you might check is the cam roller on the linkage at the top above the carbs. There is a post/roller for the cam, it should be about 3/8 inch in diameter with a clear looking outer shell. Over time the outer shell wears and brakes off, leaving just the black, inner section about 1/4 inch in diameter. When this happens, it throws off the adjustment and can cause your low idle to suddenly show up.

[rboat]

The engine was running smooth and making RPMs. The screw I turned was the idle adjust screw that was pointed out in my service manual. I did not mess with anything else, linkage or otherwise. I checked for the mentioned broken wires or worn parts but could not find any. I just thought it was a bit strange that the idle was a bit lower and harder to keep it running after replacing the spark plugs with exact replacement new ones. Could the culprit possible be old gas? I use stabil, but the engine had not been run for about a month. Thank you for your help.

[tnriverluver]

The last time I did something very similar to an old Merc 115 tower of power I ended up burning 2 cylinders because the timing was now out of sync with the throttle linkage.  If you don't know what you are doing please take it to a Professional before you have an expensive lesson like I did.

[Kevin22]

Did you check the gap on the plugs before installing? Take them back out and see what they look like, see if they are fouled bad then check the gap before installing. Also call evinrude and ask them what the recommended plug is for your motor. Sometimes on older motors they will now recommend a different plug that they have found works better than the one in the manual. 

[Way2slow]

I don't think I would be asking Mercury anything about an Evinrude motor.

[Kevin22]

Sorry, was thinking of the problem I recently had with my Merc while typing. Meant to say evinrude. 

[rboat]

Thanks guys, I did check the gap before installing the new plugs. The plugs were recommended by evinrude because that's who I ordered them from and they were the exact same # as the ones I pulled out. Everything should still be the same. I am not a total newbie to engines and I would not mess with anything I do not understand, but a 1/4 turn of a carb. idle screw should not be total doom. Thank You for your ideas, and if anyone has any other suggestions please let me know.