1985 Johnson 175 Lean Idle Sneeze Re-Visited

Mugsey

Seaman Apprentice
Joined
Aug 4, 2007
Messages
41
First of all thanks Gary H NC for some good advice on my lean idle sneeze. I used toothpicks while the motor was running and carefully blocked the lean idle jets and discovered its only the top carb causing the problem. My jets are #33 which is standard. How small should I go on replacement jets ?
 

Boatdood

Seaman Apprentice
Joined
Aug 22, 2008
Messages
43
Re: 1985 Johnson 175 Lean Idle Sneeze Re-Visited

Mugsey, a few years ago I went to test run an engine with a similar problem as yours and had one of the OMC factory service reps with me. He pulled out his kit of jets to find the best size for that particular engine and actually had some orifices that had no hole whatsoever in them. So I guess that's how small you can go; no air bleed at all. Shortly after that episode I came up with my own method of finding the best size to make the sneeze go away. I modified a small punch on a bench grinder so the tip would fit into the air bleed orifice but still be slightly larger than the hole. Then I could tap on the punch lightly which would gradually close the hole in the brass orifice. Sure did make it easy to find the right size and it eliminated messing with and dropping all those little rascals. Just stop tapping when it quits sneezing. Give it enough time between taps to see how it reacts so you don't go farther than you need to. It's a little harder to open them back up, but I do use a pin vise and a set of tiny drill bits to do that as well, but you've got to take them out and drop them a few times.
 

Mugsey

Seaman Apprentice
Joined
Aug 4, 2007
Messages
41
Re: 1985 Johnson 175 Lean Idle Sneeze Re-Visited

Sounds like a good plan of attack I'll give it try. The motor ran best when the jets were almost totally obstructed so I know which end of the scale to start on. Thanks.
 
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