How to Rebuild a Yamaha Outboard Carburetor

by Andrea Walk

Yamaha is well known for manufacturing motorcycles, both for street and trail riding. However, the company also manufactures outboard boat motors. The carburetor on the Yamaha outboard transports fuel from the tank to help the motor accelerate when the throttle is engaged. If the engine seems to stall or have trouble accelerating when the throttle is opened up, it may be a sign that the carburetor is clogged. If this is the case, the carburetor should be removed, dis-assembled, cleaned and then rebuilt. It will take four to six hours to rebuild the carburetor.

1.

Remove the engine cover and then use a Phillips screwdriver to loosen the fuel primer bulb hose clamp on the engine. Pull the hose off.

2.

Use a pair of pliers to remove the throttle linkage from the throttle arm on the carburetor and the choke linkage from the choke lever.

3.

Use a nut driver to remove the nuts holding the carburetor in place and set them aside. Lift the carburetor gently from the motor.

4.

Remove the low speed needle with a screwdriver.

5.

Hold the carburetor over a bucket and use the screwdriver to remove the float bowl screw. Allow any trapped gas inside the float bowl to drain into the bucket. Also remove the gasket from between the float bowl and the carburetor body. If is is in bad shape, toss it out and replace it later with a new gasket from the carb rebuild kit.

6.

Use a screwdriver to remove the float and valve, along with the nozzle and main jet. Mark or tag the jet screws in some fashion so they can be put back correctly later and then remove them with a screwdriver from the carburetor body.

7.

Clean all the loose carburetor parts well with spray carb cleaner. Also spray out the float bowl and all of the open jet holes and ports. Allow at least an hour for the parts to air dry.

8.

Replace the carburetor jets with the screwdriver, along with the float and valve, main jet and the nozzle.

9.

Apply gasket sealant to the new float bowl gasket from the carburetor kit and then place the gasket against the bowl. Screw the float bowl back to the bottom of the carburetor. If the low speed needle is worn, replace it with a new one from the carburetor kit with the screwdriver.

10.

Set the carburetor back in place on the manifold and use the nut driver to install the retaining nuts.

11.

Replace the choke and throttle linkage with the pliers.

12.

Slide the primer bulb hose back onto the engine port, tighten it with a screwdriver and then replace the motor cover.

Items you will need

  • Phillips screwdriver

References

About the Author

Andrea Walk began writing in 2001, authoring user guides for technical software. She holds a Bachelor of Arts in political science from Loyola University, where she was a member of the Dean's Grade Review Committee for English. Walk is a member of the Automotive X-Prize team Global-E.