I have a Yamaha F50 tiller, 4 stroke outboard, of 2000 +- vintage, on a 16' Sylvan boat. Motor is a Canadian motor.
Have used it a little. As it doesn't seem to run as well as it should, I pulled the plugs and found they were, NGK DPR8EA-9.
Sticker on motor says use NGK6EA-9. So the new plugs are now NGK6EA-9.
The old plugs were really fouled black and wet. New fuel with Yamaha Ring Free fuel additive added to help with carbonization issues. Previous owner had used Seafoam additive.
Why would the existing plugs be two heat ranges colder? All the owner could find, assist with slow trolling use, altitude (5000'-5500' use)? My son was here with his boat, with 40hp 2 stroke Johnson, and he said his motor was off with less power due to altitude?
Maybe get to try it on the lake tomorrow, if the T storms stop?
Thoughts, ideas, appreciated! Thanks in advance.
BTW, lots of small issues to resolve yet, get live well, bilge pump, tach unit working.