Yamaha F100B F100C Outboards Factory Service Manual, Page 86Get this manual
Fuel system
Checking the carburetor
1Check the air and fuel passages, and jets for dirt and foreign matterClean the carburetor body with petroleum based solvent if necessary2Blow compressed air into all passages and jets
Checking the check valve
1Install the special service tool onto the check valve
CAUTION:
Direct the compressed air downward, otherwise cleaning solvent may be blown into your eyes or small parts of the carburetor may be blown off Do not use steel wire for cleaning the jets, otherwise the jet diameters may be enlarged, which may seriously affect performance3Check the main jet 1, pilot jet 2, and main nozzle for dirt or residueClean if necessary