Originally Posted by 9D280
My best guess would be a mariner. Mariner haven't made their own kit for yonks, and have bought both Yam and Merc engines.
So if you have a Yam, the other is most likely a mariner.
I'd be disinclined to agree here. The Yam based Mariners only went up to around 55/60hp, the larger hp models being re-branded Mercs, which have different lower units to the Yam V4.
It may be worth checking out the 4-cyl Twatsoo 120/140hp, as some of their motors are derived from 'old skool' Yams, but I wouldn't hold out much hope.