Every small outboard
Ive owned has those same stainless bolts running through aluminum threads. Every one froze up and gave constant problems even after coating with lanolin grease or whatever. The darned merc 3.5 that I bought new also had a tight fitting shift lever that was stainless running through an aluminum hole that would also freeze up after a short time of sitting. Then they put a plastic handle (replacement $75) to break off. (that motor
lasted about a month longer than warranty)Well last time the securing bolt froze then broke I got sick of it and found a cheap
fix. I drilled the aluminum threads out and used 2, 3/8" bugle head
bolts with nuts on inside and out. Backing the inside nut out to tighten the bracket to the transom, and the other so the bolt doesnt fall out while transporting. They take an extra couple of minutes to tighten and a 9/16" wrench but Ive never been sitting there cussing at the stupidity of the setup. cost about $1 instead of the $24 per bolt assembly yamaha was asking. Might also deter a thief of convenience being you actually need a tool to remove the engine
from the transom.