simyamaha.com or boats.net will have that part. You will need to set the throttle linkages. There's one carb that has a set screw on the side of the carb to set the throttle plate, its pointing down. Back that screw off till its not touching teh linkage, now look at the linkages from the side, you will see a screw on each carb, they are left hand threads, break each one loose, shouldn't take ore than a half turn, 1 turn at most. Flip the throttle plate open and closed, making sure the plate is all the way closed, then tighten the screw(remember, its opposite threads) Do the top carb first, then the bottom one, the center carb has the piece that contacts the linkage from engine, there's a line on that piece that should line up to the roller. Hers a couple videos
https://search.yahoo.com/search?fr=m...150+carburetor