Check Those Jets!

[Jerryda96]

Just re-jeted my carbs on 1990 90 HP Evinrude. It always had a rough and shaking idle. Now it's great. I found out that one of the .026 jets was smaller than all the rest. I got into the better half's sewing box and found a needle that would go through the other three but not the fourth. So I guess I had a cylinder running lean all these years. Spark plugs did not show this.<br /> Now to figure how to lower the idle. Anybody know what it should be?

 

[MGuckin]

Re: Check Those Jets!

I would say about 750-800, warmed up, in gear and in the water, not on muffs.

 

[seahorse5]

Re: Check Those Jets!

Idle is 650-750 in gear.

 

[72 mako 19]

Re: Check Those Jets!

run engine and put it in idle. turn idle screw a quarter of a way each time and see how engine responds. before it dies out or backfires is the minimum idle your engine can take. use that setting and you are set.

 

[Jerryda96]

Re: Check Those Jets!

Thanks for the info guys. I'll try them out this weekend. It's idling at 900 right now which seemed a bit high.

 

[seahorse5]

Re: Check Those Jets!

Your 90 has fixed idle air bleed jets, there is no screw to adjust the mixture on the carbs. The only adjustment you have is the idle speed.<br /><br />Boat tachometers (except digital) are not accurate enough at idle settings to make the adjustment. That is why good techs use a shop tach or portable digital to set the idle speed.