Best sparkplug for 85 Merc 25

[Merc25XD]

I saw a bunch of black oily stuff coming out of the exhaust hub today. I suspect that it is unburned fuel. I have been doing alot of trolling lately so I'm sure that is the reason why. What sparkplug is recommended for my 1985 Merc 25 if I do a lot of trolling. I am not sure of the current sparkplug number, but I know that it is not a standard adjustable plug. I have a new set of NKG's BP8H-N (10). Would this plug function better for slow trolling and not drip black spent fuel out of the exhaust? OR...am I just stuck with this normal problem with my Merc?
Anybody recommend a good plug to use for trolling?? Thanks.....

 

[Laddies]

Re: Best sparkplug for 85 Merc 25

That is a good trolling plug in most 25's you might try a idle adjustment if they don't help

 

[Merc25XD]

Re: Best sparkplug for 85 Merc 25

Went fishing today on Lake Michigan with my 14' Lund and my 25 merc. As Laddies suggested, I did a little minor tweeking with the carb...I mean minor. I checked the plugs before I went out and just wiped them off a little. The plugs are NKG's BUHW's. I trolled for 5 + hours and not a problem. When it came time to head back to the launch, I pulled up all my fishing stuff and cranked it up...
It never missed a lick...I am afraid to crank it WOT, it really flies at half throttle.
Thanks again Laddies for your input. Oh...I did catch a small brown trout which my wife and I had for lunch today...mmm good.

 

[Laddies]

Re: Best sparkplug for 85 Merc 25

We are still froze in up here, the ice fishing is still going but it's about done till ice out.