Merc carb adjustment

[Sugo]

I have a 1994 Mercury 135hp outboard. I have removed the carbs, soaked, cleaned and flushed them out. On all 3 carbs I have set the mixture screws to 1.5 turns out from lightly seated. Each carb has a 2 mixture needles (one on each side of the carb) I assume one is for idle and the other for high speed. I further assume the needle that corresponds to the smaller jet is the idle and the other is high speed. Can anyone confirm my assumptions and recommend a sequence to correctly adjust them. My shop manual does not have much detail on this. Thanks for any help.

 

[cr2k]

Re: Merc carb adjustment

The screws are all idle mix one for each side of the carb.

 

[Chris1956]

Re: Merc carb adjustment

Sugo, As was said, all the screws are for idle mixture, one for each of the six bbls of the 3 two barrel carbs. High speed jets are fixed and not adjustable.

The bad news is that you will need to adjust all six to get a reasonable idle. The good news is that the motor is not real fussy about the idle settings, so you have a chance to get them pretty close. I would warm the motor up in the water, cowling off and idle around in gear while adjusting for max RPM. After you achieve that try accelerating. If it stumbles, open both needles on the top carb 1/8 turn and try again. Follow with mid carbs and then bottom carbs testing acceleration after every adjustment.