Yamaha F100B F100C Outboards Factory Service Manual, Page 13Get this manual
Features and benefits New plastic-region tightening bolts To tighten the plastic-region tightening bolts, tighten them to the specified torque, and then tighten them to the specified angleBy tightening the bolts to the specified angle, they are contracted to more accurate torque, making periodic maintenance checks and adjustments to, as well as additional tightening of the bolt unnecessaryThe cylinder head bolts, connecting rod bolts, and crankcase bolts have adopted this method to help better control torque accuracy