Spark Plugs 2002 115hp fourstroke

[portd]

I have noticed for the last 2 years when i replace spark plugs after about 80 hrs each year that the top plug The white insulator is black the other 3 are normal but it is not fouled . plugs are LFR6A-11 NGK . I can pick the top plug out of the 4 no problem just by the colour difference . 2002 115hp fourstroke EFI I think about 350 hrs . oli used is 25w40
I do a lot of trolling . i have never serviced or checked thermastat . any thoughts could this be linked to valves or nothing at all , motor runs perfect

 

[Texasmark]

Re: Spark Plugs 2002 115hp fourstroke

On that few hours one wouldn't suspect anything catastrophic like worn valve guides. Leaking seals I think would tend to think would more affect the lower cylinders. Your tstat is probably at the top of the engine so when it opens, it would have hot water longer than the rest of the engine but that wouldn't account for the excessive oil. However, if the engine has a separate carb for each cylinder, that could be soot from too rich a mixture meaning your carb could be out of adjustment or crudded up, float not seating properly... Sticking rings could account for it on the mentioned cylinder.

Might double up on the Sea Foam (2 oz per gallon) for a couple of tanks and see what happens. It would go after both potential problems and you wouldn't be unnecessarily chasing a ghost if it cures the problem.....I mean why tear things apart when all you have to do is a little chemical cleaning.

HTH,
Mark