2009 Yamaha F40 Outboard Service Manual, Page 182Get this manual
Power unit (check and adjustment) Pulser coil air gap a: 0.351.35 mm (0.0140.053 in)
Adjusting the pulser coil air gap
1Loosen the pulser coil bolts and adjust the pulser coil air gap
2Tighten the pulser coil bolts a, and then check the pulser coil air gap again