NGKBR8HS Plugs in c115 motor temp range

[ROB]

1997 C115 runs great except, I foul plugs when fishing at slow speed. I used the Clymers shop book to adjust the pilot screws this helped. Manual said 3/8 to 7/8 I'm at 1/2.
I use Sea Foam in my fuel for carbon reduction.

Would a next step hotter plug help? ngkBR7HS
7 being hotter according to NGK home page.
Thanks.

[boats.net]

I would not recommend a hotter plug. It should have BR8HS-10 plugs gapped at .039 and use a 50:1 oil mixture.

[Ken]

Rob,
I have the same motor - a 2000 C115, and am using the same plugs.
I agree with boats.net guy - you do not want to go to a "hotter" plug.
Even though you adjusted the pilot screws per the manual, you may still be running a little rich at low speeds due to gum/varnish buildup in the carbs. Might try a shock treatment with SeaFoam/RingFree.
I have found that some TCW-3 oils burn cleaner than others. I am currently using Pennzoil synthetic blend - you might give it a try.
Since you are doing a lot of low speed running, you need to go WOT for short periods of time during the course of the fishing trip to help blow out/clean the carbon from the plugs.
Also, you need to change the plugs at least once a year, depending on number of hours - I run about 100 hrs/year and change plugs once/yr.
And at the gas pump - for a 50:1 gas/oil ratio - you need to put in 12.5 gal gas for 1 qt oil.
Good luck [img]smile.gif[/img] ,
Ken K

[ROB]

Thank you both.
I looked at the 150 6 cylinder motor specs
and they want the #7 plug in my model year.
I use proper oil mixtures with quality oil.
Despite your recomendations its getting hotter plugs.
With proper oil mixture and not holding WOT the motor should be fine. If not I'll be purchasing a
four stroke after I blow it up!
Again thanks for your concerns, just have to try this after all other recomendations were followed.

[ROB]

Dear Boats.net you said my c115 motor should
use BR8HS plugs.
In the Clymer shop manual there is an Exception for the C115 Motor stating to leave the R out so would
B8HS-10 would be correct?

What is different about the C115 and not having the R in the plug #. Could this be my fouling problem if I had the R plugs in?

PS I never went to the hotter plugs either.
Thanks again for any education in this plug # system.