How to synchronize carbs?

Capt dave 258

Seaman
Joined
Jul 14, 2021
Messages
52
I have a 2001, 80hp carbureted 4 stroke Yamaha. Can someone direct me to the procedure for synchronizing the carbs? Put fresh plugs in it and after one season they are all carboned up. Thanks
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
9,135
find the Yamaha service manual for your motor, it will have the procedures.

but I would think the carbon build up comes from burning oil
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
9,135
also just to let you know ,you have to close all of the throttle plates completely, not just with them sitting on the idle screw.
and then hook up the linkages between the carbs.
then adjust the idle speed screw to have all throttle plats opened exactly the same amount.
then mess with the idle mixture screws

you cannot have some throttle plates open more than others
 

lelyyy

Recruit
Joined
May 14, 2025
Messages
5
Yeah, I had a similar issue with my engine a while back. First thing I checked was the oil level, just to make sure it wasn’t burning oil too quickly. Then I borrowed a vacuum gauge to compare the vacuum from each carb and started adjusting them slowly. It was really a hassle. I didn't do it properly before, and the car was shaking a bit when driving.
 
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