2005 Yamaha F90TR 90HP Outboards Factory Service Manual, Page 143Get this manual
Drive shaft and lower case 6Install the propeller and propeller nut, and then tighten the nut finger tightPlace block of wood between the anticavitation plate and propeller to keep the propeller from turning, and then tighten the nut to the specified torque7Fill the gear oil to the correct level WARNING
Do not hold the propeller with your hands when loosening or tightening it Be sure to disconnect the battery leads from the battery and the clip from the engine stop lanyard switch Put block of wood between the anticavitation plate and propeller to keep the propeller from turningNOTE: If the grooves in the propeller nut do not align with the cotter pin hole, tighten the nut until they are alignedPropeller nut 4: 34 Nm (3.4 kgfm, 25.1 ftlb)