‘90 Yamaha 25 hp 2 stroke carb

[ultra353]

i rebuilt the carb on the mentioned motor and I can’t recall on the air screw setting. I’ve seen the standard 1 1/2 turns out to 2 2/8 turns out. Does anyone know for sure? Thanks
The manual calls for 100:1 on the oil ratio, seems pretty lean to me.

 

[GA_Boater]

Don't know the gasil ratio.

The idle screw setting is a starting point to allow the motor to start. The final adjustment is done at idle in gear in the water. You can back the boat down the ramp, still tied down to the trailer and do the final adjustment in forward. Turn the screw in until the motor begins to stumble and turn it out while counting the turns until it stumbles. Set the screw at the mid-point.

 

[ultra353]

Thanks GA_Boater, I’m more of an E/J guy and I’m not sure on the Yamaha setting . There is a video posted where the under the hood decal calls for 2 3/8 turns out for a starting point on a Yamaha 25hp 2 stoke.I’ll just try each one and see what happens.

 

[boscoe99]

The setting is two turns outward from being lightly seated. Plus or minus 3/4ths turn.

A number of Yamaha pre-mix models run on 100/1. Completely normal.