I had a 40 mariner at the same time as my mate had a 40 yammie. Same engines different colours both engines equipped with electric and recoil start which was always a handy safety feature beach launching thru surf. His was 100:1 mine at 50:1 . We ran them both at the same sorta skinny 50:1. If 100:1 is good 50:1 must be better sorta attitude. Had that engine for 17 years-never missed a beat and it had an awful lot of use, we live just back from the beach and those were the days of Jumbo cod around here, the boat was always out in winter if the weather was anything like good enough-oh happy days, we thought they'd never end......they did with the help of the european fisheries policy