Yamaha F9.9B Owner's Manual page 104

Trouble
E. Engine vibrates
excessively.
5-3
Possible Cause
1. Propeller damaged.
2. Propeller shaft damaged.
3. Weeds or other foreign matter tangled
on propeller.
4. Motor mounting bolt loose.
5. Clamp screw is loose.
6. Steering pivot loose or damaged.
Remedy
1. Have propeller repaired or replaced.
2. Have serviced by a Yamaha dealer.
3. Remove and clean propeller.
4. Tighten bolt.
5. Tighten the clamp screw.
6. Tighten or have serviced by a
Yamaha dealer.
E