2009 Yamaha F40 Outboard Service Manual, Page 224Get this manual
Camshaft and valve
11Tighten the cylinder head anode plugs to the specified torque12Install the spark plugs B, and then tighten them to the specified torque13Install the engine hanger C
Cylinder head anode screw A: Nm (0.2 kgfm, 1.5 ftlb) Cylinder head anode plugs z: 18 Nm (1.8 kgfm, 13.3 ftlb) Spark plug B: 18 Nm (1.8 kgfm, 13.3 ftlb)