Everyone Raves about Yamis and yet there seems to be some bashing of the Mercs. My 115 Merc has a Yami Powerhead, so do I have to worry about black death, or is my motor bulletproof. So many of the manufacturers are in bed with each other that you really never Know who or where it was put together.
Every manufacturer has a line that may have it's share of problems. I really don't think one manufacturer has a huge reliability lead over another these days. Like any piece of mechanical equipment you may have the bad luck of getting a lemon. Maintenance and upkeep is also a huge factor with outboards. Some guys are better at keeping there equipment up and running than others. Is it a result of the manufacturer because of years of trouble free reliability. Or is it because the operator doesn't abuse his engine, changes the oil religiously, greases everything on schedule and basically babies his machine.
I really don't know, maybe I've just been lucky and never ended up with a lemon. I have owned Mercs, Johnsons, Yamis, & Hondas and really can't see any huge reliability advantage in any of the motors I have owned. I have been happy with all the outboards I've owned. IF I had the choice when repowering with 4 strokes I would probably lean towards Honda or Yamis. I purchased my boat from my Cousin because I knew it had been well taken care of and I have found the 4 stroke Merc on it a very good motor.
BTW, I still have a Merc 9.8 outboard that my dad bought me when I was 13. I'm 49 now and it still runs like a top. Of course being a smokey old 2 stroke it rarely sees use these days.