Hotter plugs for Mercury 2 stroke?

[wingssail]

So I am doing some maintenance on my 20 year old Merc 2 stroke, which I love, and one problem I want to solve is that it runs on one cylinder when it's cold, for about 30 seconds to a minute, then runs on both and is fine. If it does not start immediately then it can get to be a bear to start (I can do it but Judy cannot).

It seems like a spark problem to me (but maybe not).

I've pulled the pugs, they are the recommended plug NGK BP8HS 15. The both look OK, a little bit wet, but not dirty or burned. But they are old and rusty.

Should I go for a hotter plug or just put new ones in?

[rbk]

Find the correct plug type and install new ones. Don’t assume the one installed are the correct type. Merc 2 strokes do tend to run hot though. I’ve got a straight 6 merc that uses NGK BUZHW with no standing electrode as they tend to burn off rather fast. And by hot I mean strong ignition not cylinder temp.

[jimbunyard]

You might also try changing the coils and cleaning all (or as many as you can easily get to) electrical connections. The coils' performance can deteriorate with age, and you already know what the marine environment can do to electrical connections...